Jupiter Lighthouse
Jupiter Lighthouse (ジュピター灯台, Jupiter Lighthouse), the Jupiter-aligned of the Elemental Lighthouses, is a very significant storyline dungeon in Golden Sun: The Lost Age. Located near the north edge of the southwestern continent of Atteka, it lies within walking distance of the town of Contigo, the modern-day settlement that has based itself around the ruins of the ancient Anemos culture. As a lighthouse, casting the Jupiter Star jewel into its aerie will light the tower's respective Jupiter Beacon to expose the world to Jupiter elemental power. Should all three other lighthouses throughout Weyard have their beacons lit at the same time as Jupiter, the free use of the reality-bending force of Alchemy will be returned to the world via the Golden Sun event.
The Shaman's Rod, which Contigo had given to Master Hammet years before the GBA games, is presented as early as the first Golden Sun as required to "reach" Jupiter Lighthouse. This is because the Hover Jade, which contains the Anemos tribe's Hover Psynergy that allowed them to fly, is required by the mechanisms in the structure itself to gain admittance. The Hover Jade and the Shaman's Rod had been exchanged between ancient Contigo and Shaman Village in the continent of Hesperia up north, and Shaman Village awaits the return of their rod.
Walkthrough
Jupiter Lighthouse's icon on the world map can technically be entered as soon as the Western Sea is first reached late in the game; sailing through the rivers of Atteka from its southeast to reach Atteka Inlet at its southwest, then proceeding northwest past Contigo, will bring you to it. It might not even be considered all that "worthless" to come here this early because the very limited portion of the dungeon that is accessible by default allows you to collect two separate Mints. You can only expect to enter and play through this dungeon properly, however, by bringing the Hover Jade won at Trial Road far to the north at Shaman Village in Hesperia. Whenever you end a turn of battle at Jupiter Lighthouse, Jupiter Adepts in your party like Sheba will recover 4 PP.
If you have the Hover Jade, enter the physical structure and follow along the narrow path west and then back outside to a purple "Cyclone portal". Before you take that portal, blow away the weeds southeast of it with Cyclone to uncover the first Mint. Then, cast Cyclone on the portal to be transported underground, and reach the T-intersection branching up and down; head south to the clumps of leaves and blow them away with Cyclone as well, and you will fight a Mad Plant that drops the second mint. Now head north, where a cave door leads to a room with a Psynergy Stone, then head east to another cave door. Cast Hover while standing on the purple circular tile and "walk on midair" to the right ledge, and follow along the path south and take the south Cyclone portal up into the main structure. Push a yellow-tipped pillar onto its floor switch to permanently open the beige slab-like doors and allow easy access from the outside entrance into the main dungeon beyond.
Main structure
The large, cluttered room you come across just past the entrance can be called the "main lobby." Enter the door to the left, then go up the stairs above the ladder; you will reach a puzzle room with broken pillars that can be rolled around. Roll the upper horizontal pillar up, then roll the lower-left horizontal pillar up, then roll the vertical pillar left, and finally roll the lower-right horizontal pillar up. Before you head south through the door, roll the vertical pillar all the way left to reach the chest off to the right, which contains the Erinyes Tunic. Go south through the exit and transport yourself upwards with the Cyclone portal.
You will end up in an area where, to the lower left, what can be informally called the "angel-flanked Cyclone portal" lies. You can go up to the yellow-tipped pillar and use the Move Psynergy to drop it near the chain if you wish, since it is one of two such pillars that will need to be dropped to allow for an optional shortcut very late in the dungeon. The important step to take, however, is to head southwest of the angel-flanked Cyclone portal, and follow along with the linear trail through multiple screens until you reach an area with a red door visible to your left (which is where the angel-flanked portal brings you up to) and a ring of pillar-like platforms to the upper right. Cast Reveal to hop across the hidden platform in the center of them and head upstairs.
You will find yourself at the north end of a large room with a massive maze of pillar-like platforms, and your goal is to reach the west ledge. Hop right twice, down once, and right twice to get onto the east ledge, then hop several times in a southwestern direction to get to the thick pillar with the wall slide and take the slide down to the darker floor. Move the yellow-tipped pillar above you all the way left and the other yellow-tipped pillar seen left of you one tile left, and move the third, leftmost such pillar all the way up. Now you can climb up to the west ledge and head to the spot right in front of the stairwell leading up, and hop right once, down once, right twice, down once onto the first yellow pillar, left once, down twice onto the second yellow pillar, left once, up twice, left twice, down once onto the third yellow pillar, and left once to reach the chest containing the Meditation Rod. Retrace your hops to the stairwell and take it up.
In the next floor's room, slide down the wall slide right next to your stairs and climb up the ladder over to the right, and follow the linear route through the next few screens; this will bring you to the aerie of Jupiter Lighthouse already, but it is currently sealed. Head into the lower-left door and go back down until you slide down another wall slide, and step up to the ladder on the central podium; a telepathic message will recite the message, Holder of the star... Show the power of the Anemos! This means climbing to the top of the ladder and casting the Hover Psynergy, which will initiate an elaborate sequence with the ancient mechanism that will make the Hover tiles underneath each of the white box-like platforms activate and cause said platforms to hover above them. This indicates that the entire dungeon has had its dormant Hover tiles reactivated. Hop east across the white box-platforms and leave the room through the doorway in the upper-right corner.
Back in the room up north, use the Hover Psynergy on the lower tile to reach the Red Key to the southwest. Push the white box-platform on the ground north onto the Hover tile to complete the set of floating box-platforms, and then climb up near them and hop west across them to return downstairs. Back in the pillar maze with the Meditation Rod chest, head out the room's southwest exit onto an outdoor balcony of the Lighthouse, push a white box-platform onto the trap door east of it, and step onto the floor switch to make it fall. This lets you return to the pillar maze through its southeast doorway, which in turn lets you return to the downstairs stairwell at the top center portion of the room by hopping northwest across several pillars.
As you go back downstairs, the ring of white box-platforms visible to the lower-right is now hovering, which allows you to hop onto its leftmost box-platform, cast Reveal to expose an invisible floating platform in the center, and hop to the right to reach a chest with a Psy Crystal. Return left of the hovering ring of box-platforms and hop west past the ring of pillars using Reveal in the same way, and retrace your steps back south and downstairs through the linear route until you eventually return to the angel-flanked Cyclone portal. Take it up with the Cyclone Psynergy and use the Red Key on the red door to unlock the path to the west "side-tower" of Jupiter Lighthouse.
West side-tower
The outdoor bridge to the west side-tower does not make accessing the west side-tower easy, for a large statue of a female face at the west end of the bridge will spew forth a whirlwind that will push you all the way back to the east end of the bridge. The purple blocks adorning the bottom edge of the space near the statue force you in the whirlwinds' path but feature gaps that let you avoid them. It is possible to run into the leftmost gap, then run southwest of the statue as soon as the whirlwind has passed by you. Proceed into the side-tower to a T-intersection, and fight the Mimic at the west end for a Psy Crystal.
When you head upstairs through the side-tower, you will reach a room with pillars that can be rolled. Ignore the blue key as you roll the right horizontal pillar down, and go up the stairs to a room with cracked floor tiles. Walk onto and up from the uncracked tile right of the stairwell and walk through the path without a crackable floor tile, left of the rightmost path that does have one. Some players might want to exit the south end of the room right then and there and ignore the two chests because they will require you to drop back into the floor below and cause a "puzzle reset" in this room in so doing, such as with the lower-right chest containing 306 Coins. If you want the Mist Potion in the upper-left chest, you will have to exit the door south of the angel statue and go back in to perform a puzzle reset, then remotely Move the yellow-tipped pillar left to drop it into the gap, then head back to the stairwell at the top end and walk over the uncracked floor tile at the northwest corner of the room in order to hop onto the pillar.
Follow the route up through the floors of the west side-tower until you reach a room with a mass of cracked floor tiles, some already in partially pre-cracked states. Walk to the left Hover tile and use Hover to land on the solid ground at the west edge, and Move the yellow-tipped pillar onto the floor switch to open the southeast beige door. Now carefully walk across the uncracked tiles all the way to the northeast hover tile, and hover straight south so that you can walk through the open beige door below. As you run to the southwest exit, take care not to fall through the cracked floor tile just two tiles south of it, or you will have to go through this puzzle all over again.
You will soon reach the peak of the west side-tower, and move the "conduit block" next to the archer statue into the open hole, which will prompt the statue to fire a magical arrow at the seal of the aerie in the main tower. Now you will need to collect the Blue Key at the base of the west side-tower. Go back inside and drop through the cracked floor tile so that you can return to the puzzle room with the many cracked floor tiles, and use the northeast Hover tile to make it to the lone pre-cracked tile just northwest of the beige door. Fall through that and you will eventually fall right next to the Blue Key. At this point, given that your next destination is the main lobby of Jupiter Lighthouse, casting Retreat will save a good deal of time getting back there.
Back in the main structure
Back in the main lobby, go through the northwest door again, but climb down the ladder and cast Move on the white box-platform at the east end to move it left onto the exposed Hover tile to make it float. This will let you hop east across the five box-platforms and go through the northeast upstairs stairwell. Follow along through the crumbling trail until you reenter the main lobby through its east elevated doorway, and push the conduit block off to the left so you can slide down and Move it into the hole. The newly reactivated eastern Hover tile lets you get onto the ledge with the west Hover tile near both the northeast Cyclone portal and the pulsing beam of energy at the center of the lobby.
Take the northeast Cyclone portal up and head through the door to an area with a lone angel statue. The yellow-tipped pillar at the north end can be Moved left onto the gap near the dangling chain — and if you cast Whirlwind to swing across the chain, you will find the other chain near the other pillar you had dropped next to it some time ago, near the angel-flanked cyclone portal. These two swinging chains now constitute a special "shortcut" between the east and west sides of this floor of the main structure, though it is ultimately optional whether to actually use this shortcut later.
Regardless, head southeast of the right swinging chain and out onto a balcony of the main structure, where a block with a "lightning rod" on it can be slotted into the hole right of it. This will cause a brief cutscene where a lightning bolt will strike the lightning rod and activate a Hover tile on the upper level. Backtrack to the main lobby and onto the Hover tile just right of the pulsing energy beam, and use Hover and walk straight into the beam to be transported high up into a room with floating white box-platforms. If you want the Potion in the chest at the west end of this room, climb down the ladder and cast Move to move the leftmost box-platform onto its adjacent hover tile so that you can hop onto the west ledge. Proceed out the southeast door.
When you reach a blue door, ignore the Cyclone portal that will drop you onto the floor below without offering another Cyclone portal back up, and use the Blue Key to pass the blue door. Follow along to the higher-level eastern balcony with the Hover tile that was turned on by the lightning bolt from earlier. As soon as you Hover on this, the giant female statue will immediately spew forth a whirlwind that will forcibly transport you to the entrance to the east side-tower.
East side-tower
As soon as you step into the east side-tower's entrance, enter the doorway in front of you instead of the stairwell right of that. You will enter a puzzle room with a Jupiter Djinni. Hover onto the right ledge so you can push the "corner conduit block" south off the ledge, then slide down and push it into the lower-right hole to activate a northeastern Hover tile. Use that tile to reach the north ledge with the "straight conduit block" and push that down, then slot it into the hole right of it. This will allow you to proceed upstairs to the next floor.
But if you want to get to the Jupiter Djinni, you need to make the lower-left Hover tile light up next. Hover to the now-raised stake at the upper right and Pound it down to eject the conduit blocks from their holes, and push the corner conduit block to the lower-left hole and the straight conduit block into the hole right of that. Once you have deposited yourself in front of the Djinni, save before battling it in case it runs away and you have to perform a puzzle reset to get it to respawn. Once you have acquired the Jupiter Djinni Whorl, you can actually use the same lower-left Hover tile to reach the northwest stairwell rather than Pounding the stake again.
The next floor also features a stake that must be Pounded to eject a nearby conduit block, which will deactivate the room's hover tile network and make the various white box-platforms lower to the ground. Move the block to the midpoint between the stairwell and the upper-right ledge so that you can hop to said ledge and climb down to where the box-platforms lie. You will have to spend some time slowly moving the box platforms onto dormant hover tiles so that returning the conduit block to its hole will make them float, providing an elevated route you can hop across.
If you want the chest that contains a Water of Life, you must place one platform two tiles west of the starting northeast platform, then one two tiles south of that, then one one tile east of that, then one two tiles south of that, and finally one two tiles east of that at the southeast corner. Regardless, to complete the path to the southwest ledge, have one platform two tiles west of the default northeast platform, then one platform two tiles south of that, then one platform two tiles west of that, then one platform two tiles south of that, and finally one platform at the southwest corner two tiles west of that. South of this room, you can push the yellow-tipped pillar onto the floor switch if you want, but you need to go upstairs two floors.
You will enter a room with cracked platforms and giant female statue heads that will spew whirlwinds when you cross their sights. There are two routes through this obstacle course; one is to pass over the floor tile to your left and follow the solid ground that winds south, then pass west over the floor tile underneath the square pit so you can reach right in front of the lower-left statue. It will blow you across the lower pit to right, and you can walk east over the non-cracked floor tile to reach the solid ground that will lead to the lower stairwell. (The other route is to walk over the right floor tile at the top, walk to the enclosed area around the northeast statue, and use the space two tiles in front of the statue head to provoke it into spewing a whirlwind that you can dodge; you have a brief window of opportunity to run over the uncracked floor tile underneath the statue head, and then you can walk onto and then right off of the uncracked floor tile underneath that.)
The next floor is almost completely covered in active hover tiles, which effectively force you to stay aloft during your time in either "wing" of the room. To get the chest at the northwest corner of the room, hover into the west wing and go south around the spire southwest of the lower-left whirlwind statue, which gives you just enough room to float up past the spire's left edge that the statue's whirlwind will miss you. To reach the chest beyond two spires blocking a direct route to them, position yourself two tiles under the left spire, then float over the cracked floor tiles left of the spire and make it over the Hover tiles just above them in time to refresh your "air-walking time" and avoid falling onto the cracked floor tiles. The chest contains the strong Phaeton's Blade light blade.
Hovering past the giant statues in the east wing of this room to reach the stairwell going up operates on the same principles, but this version is arguably even more dependent on split-second timing to pass. Hover onto the tile just below the rightmost spire, then hover over the right strip of floor tiles. You need to return to the hover tiles left of the strip at just the right moment because, if you move northwest too early, the whirlwind spouted by the upper-left statue will catch you and make you fall through the cracked floor tiles — but waiting too long will make you fall onto the cracked floor tiles anyway. Once you finally reach the stairwell, you will soon reach the east side-tower's respective archer statue, and fitting the conduit into the hole here will finally unseal the well atop the main structure of Jupiter Lighthouse.
Final climb to the aerie
Your goal is now to reach the aerie of the main structure, but there are two methods of getting there from the east side-tower. It is arguably easier to just cast Retreat, return to the main lobby, and begin your climb back through the tower using the northwest doorway, up until you reach the angel-flanked Cyclone portal from much earlier.
However, the "official" way to get to this same spot would be to drop back through the various cracked floors of the east side-tower and go down stairwells until you eventually exit through the side-tower's main entrance, then cross the bridge back west, cast Lash on the coiled rope, and climb the tightrope down. This will bring you to the east part of the large horizontal area with the swinging chains you had dropped yellow-tipped pillars near previously, and you can now use Whirlwind to swing west across both chains and make it to the area underneath the angel-flanked Cyclone portal.
As soon as you take the door out to the balcony south of the angel-flanked portal, you will suddenly be presented with a dramatic cutscene. Once you regain control, follow along the route you originally took to make it upstairs to the maze of pillars with the Meditation Rod chest, and slide down the southeast wall slide. When you climb up the southwest ladder, an NPC will block you from going north to the upstairs stairwell and heal your party before directing you to the doorway to the elevated balcony. The lengthy cutscene that transpires there will temporarily remove Jenna and Sheba from your party and deposit you back in the Meditation Rod room, and now you can fairly easily follow the route up to the aerie of Jupiter Lighthouse.
When you approach the open well at the aerie, answer "Yes" to the question "Cast the Jupiter Star in?" to initiate the cutscene that will eventually force you into a unique boss battle with two opponents at once, which will last two turns. Focus on defending until the next cutscene restarts the fight with Jenna having rejoined your party, and do so again until one more cutscene restarts the fight with Sheba having rejoined the party as well. This then becomes the only "challenging boss battle" in the GBA duology that the player is allowed to lose without getting a game over, with different cutscenes for respectively winning or losing that will allow you to progress with the main plot of the game regardless. If you win the battle, though, you will gain both a nice EXP and Coin payout and the first Dark Matter your party can have access to. Whether you win or lose the battle, the cutscenes that take place will deposit you back at the base of Jupiter Lighthouse, and you are now free to return to Contigo.
Enemies
| Bestiary of Jupiter Lighthouse | ||||||||||
| Monster Name | LVL | HP | ATK | DEF | AGI | EXP | Coins | Weakness | Drop | Drop Rate |
| Blue Dragon | 32 | 408 | 349 | 121 | 133 | 490 | 297 | 
|
 Rising Mace
|
1/64 |
| Devil Scorpion | 32 | 181 | 308 | 121 | 126 | 284 | 180 |
|
 Antidote
|
1/8 |
| Foul Mummy | 32 | 238 | 320 | 100 | 118 | 376 | 297 |
|
 Potion
|
1/64 |
| Ghost Army | 32 | 250 | 342 | 136 | 133 | 454 | 254 | 
|
 Mist Potion
|
1/64 |
| Macetail | 32 | 284 | 327 | 105 | 110 | 426 | 248 | 
|
 Vial
|
1/64 |
| Wyvern | 32 | 340 | 339 | 108 | 149 | 469 | 284 |
|
 Aeolian Cassock
|
1/64 |
| Mad Plant (unique) | 35 | 726 | 352 | 99 | 152 | 1065 | 594 |
|
 Mint
|
1/1 |
| Mimic (unique) | 35 | 907 | 349 | 108 | 204 | 1420 | 700 |
|
 Psy Crystal
|
1/1 |
| Jupiter Djinni (Whorl) (unique) | 32 | 852 | 273 | 84 | 233 | 965 | 643 | 
|
N/A | |
| Agatio (boss) | 43 | 4248 | 377 | 114 | 178 | 3000 | 3740 |
|
N/A | |
| Karst (boss) | 43 | 3186 | 354 | 107 | 235 | 2813 | 5280 |
|
 Dark Matter
|
1/1 |
Enemy Formations
- Group 1: Devil Scorpion x1-3
- Group 2: Foul Mummy x1-2, Devil Scorpion x0-1
- Group 3: Macetail x1, Devil Scorpion x0-2
- Group 4: Wyvern x1-2
- Group 5: Ghost Army x1, Wyvern x0-1
- Group 6: Ghost Army x1, Foul Mummy x0-2
- Group 7: Blue Dragon x1, Wyvern x1
- Group 8: Blue Dragon x1-2
Collectables
This massive dungeon has a "main" tower structure connected to two smaller tower structures on either side, so it is worth dividing this section by structure. In the central structure, which is thoroughly explored first, are these items:
Mint: At the ground-level start of the dungeon, when you exit the lighthouse structure out of the left entrance so that you're above a piece in the ground that you would normally cast Cyclone on, go southeast and use Cyclone on the four green patches of leaves on the ground. A Mint will be revealed for grabbing.
Erinyes Tunic: In a chest at a solitary platform in a room with four pillars you can roll around, reached by rolling the one vertically position pillar right.
Psy Crystal: In a chest to the right of a circle of pillars that can only be crossed when all the Hover patterns in the floors of the dungeon are turned on.
Meditation Rod: In a chest in a room with many hoppable elevated platforms, reached by properly arranging the yellow pillars.
Red Key: Visible on an elevated portion of a room adjacent to the room where casting Hover turns on all the Hover patterns on the grounds in the dungeon. When the Hover patterns are all turned on, this item can be reached by casting Hover on the purple circle. This is used on the red door to the west, allowing you to explore the left tower structure, and is thus mandatory.
Potion: In a chest to the left in the room you end up in when you Hover yourself into the central beam of energy-charged light in the main "hub" of the dungeon and get transported up into the ceiling.
In the west side-tower of the dungeon, these treasures can be collected:
306 Coins: In the right treasure chest in the room with two chests and tiles of ground you can fall through. You will have to fall through the ground after grabbing this chest's money.
Mist Potion: In the left treasure chest in the room with two chests and tiles of ground you can fall through. Reached by entering the room from the bottom, casting Move to move the yellow pillar one space to the left, then getting to the chest counterclockwise. You will have to fall through the ground after grabbing this chest's potion.
Blue Key: At the bottom floor of the tower structure, reached by falling down from the center of the floor above in a series of pitfalls that starts at the floor near the top. This opens the blue door in the eastern part of the main lighthouse structure, allowing you to explore the right tower structure, and is thus mandatory.
In the east side-tower of the dungeon, these treasures can be collected:
Whorl: This Djinni is reached in a room where you must push pillars with the appropriate "paths" lining their tops so that the lower circle pattern on the ground will light up purple. This must be then battled to be acquired. Afterwards, re-solve the puzzle to make the upper circle pattern light up, so you can proceed to the next room.
Water of Life: In a chest in the lower left of a room with a complex network of glowing purple Hover patterns in the center of the ground. Reached by properly positioning the yellow platform pillars so you can hop to it.
Phaeton's Blade: In a chest in the upper left of the room almost entirely covered with glowing purple Hover patterns. Dexterous moving is required to reach it.
It should also be noted that after completing both side towers, the story-heavy procession of cutscenes and battles that take place in the main structure will replace your Mythril Bag item whose description reads "Holds the Jupiter Star" into an identical Mythril Bag item whose description reads "Holds the Jupiter and Mars Stars". This item will then disappear from your inventory shortly afterwards.
History
The Jupiter Lighthouse existed in Weyard's ancient past much like the other three Elemental Lighthouses as a source of its respective element in Psynergy and Alchemy. The structure is designed to work with the Elemental Star jewel of the Jupiter element, the Jupiter Star; if the Jupiter Star, the container of the purified essence of the Jupiter element, is cast down the well at the top of the Jupiter Lighthouse, its essence would be channeled by the Lighthouse's internal mechanics and be placed atop the aerie as a spherical beacon emitting Jupiter-based energy.
Originally located near Jupiter Lighthouse on Atteka in the ancient past was the City of the Anemos tribe of Jupiter Adepts, and it can be presumed that their civilization was provided at least in part by their proximity to Jupiter Lighthouse the same way the Mercury Clan was associated with the Mercury Lighthouse. The people living in the modern-day settlement of Contigo near where the City of the Anemos used to be have either an historical account or a legend of how Jupiter Lighthouse was originally lit, but that when the power of Alchemy was sealed away, part of that process involved putting out the beacon atop Jupiter Lighthouse; according to legend, the Anemos "suffered a great disaster" when Jupiter Lighthouse's beacon was put out. Another legend passed down to those living in Contigo, however, is that siblings of Anemos heritage living in the modern day and age would eventually come to light up Jupiter Lighthouse once again against darkness; this legend seems to be specifically referring to Ivan and Hama, who originally lived in Contigo and are Jupiter adepts.
The design of some the riddles within Jupiter Lighthouse that need to be solved in order for the Jupiter Star to be properly cast into the Jupiter Lighthouse's well demands an Adept to show "the power of the Anemos", specifically, the Jupiter-based power of flight the Anemos originally exhibited. While it seems no Jupiter Adepts remain today that possess the Anemos ability to hover with Psynergy, the specific power in question is contained within an artifact named the Hover Jade, which allows any Adept that has it to hover to some degree. However, the Hover Jade was a national treasure of the Anemos in the ancient past that its bearer, the hero Yegelos, exchanged with the Shaman Village hero Hoabna for the Shaman's Rod for mutual safekeeping, and the two heroes made a vow that the two items would be traded back should the need arise. Over the ages, though, Contigo's knowledge of the location of the Hover Jade was lost; all that is known amongst those living near Jupiter Lighthouse is that the Shaman's Rod is needed to obtain the Hover Jade. During the three-year period of time prior to the eruption of Mt. Aleph, the Mars Adept warriors of Prox research all of the Elemental Lighthouses, including Jupiter Lighthouse, for their plan to light all four Elemental Lighthouses and restore Alchemy to the world; their research is why Saturos knows that in order to climb and successfully light Jupiter Lighthouse in the future, he needs both a Jupiter Adept and the Shaman's Rod for a reason he is not aware of.
Late in The Lost Age, a group of traveling Adepts led by Felix - a former companion of the now-deceased Saturos continuing the quest to light the Lighthouses in his stead - and comprised of Jenna, Sheba, and Piers, enter the Lighthouse. Felix had previously taken the Shaman's Rod from Ivan, and later visited Shaman Village and successfully exchanged it for the Hover Jade with the help of Sheba as a Jupiter Adept herself; using the Anemos-associated power of Hover, Felix's group successfully opens the well that lies at the aerie of Jupiter Lighthouse. However, a trio of Adepts comprised of Karst, Agatio, and Alex enter Jupiter Lighthouse after them, and soon afterward, a third group of traveling Adepts enter in as well, led by Isaac and comprised of Garet, Mia, and incidentally Ivan. Isaac's group pursues Felix under the belief that if the Lighthouses are lit and Alchemy is restored, the world would be put in peril, and they had previously slain Saturos and his partner Menardi in combat back at Venus Lighthouse. Karst, the younger sister of Menardi, seeks vengeance upon Isaac because he murdered Menardi, and when she and Agatio are made aware that Isaac is in Jupiter Lighthouse, they discover and learn how to operate a trap on one of the tower's balcony levels, and lie in wait.
Isaac's party soon gets caught in the trap Karst and Agatio set up; Mia falls down onto a ledge below, and Garet falls in after her, injuring his left arm and leaving him hanging on for life with just his right. Karst and Agatio make themselves known to Isaac and introduce themselves, and Isaac tries to tell them off and say he'll rescue Garet himself and then stop Felix from lighting the Jupiter Lighthouse. Karst and Agatio explain about how they intend to have him dead in retaliation for his murder of Menardi and Saturos, and then clarify that they did not seek a "fair" two-on-two fight with Isaac and Ivan; they had brought Alex with them as a third Adept. Just then, however, Karst realizes Alex has disappeared and has abandoned them, and she and Agatio vow to punish him afterward as they fight Isaac and Ivan two-on-two. This entire procession of events is witnesses by Felix's group from a lower-level balcony, and they rush up through the Lighthouse to intervene; they are suddenly approached by Alex, who states that as he was watching Felix's party witness Karst and Isaac's side in conflict, he knows that Felix won't be bringing himself to light the Jupiter Lighthouse while leaving Isaac behind in harm's way. Alex heals all of Felix's group and sends them off to save Felix's former childhood friends so that Felix would light Jupiter Lighthouse afterward.
Karst and Agatio prove too powerful for Isaac and Ivan to handle individually, and they are rendered defeated on the ground from the powerful Mars Psynergy and combat abilities of the pair of Mars Adepts. The pair are weakened from the battle because of the surprising amount of resistance Isaac put up, but before they consider killing Isaac for good, Felix's group steps in to stop them. Felix's group uses their manpower to force Karst and Agatio to agree to spare Isaac's life in exchange for Felix lighting Jupiter Lighthouse, and though filled with rage, Karst consents to this with the added condition that Felix also takes the Mars Star currently in Isaac's possession, so that Mars Lighthouse may eventually be lit in the future. Isaac states out loud that while he does not know why Felix wants to light Jupiter Lighthouse, he trusts Felix's judgement, and hands over the Mars Star willingly. Karst and Agatio head up to the aerie of Jupiter Lighthouse and beckon for Felix to come up with them while his friends remain behind to help Isaac and Ivan and save Mia and Garet, but just before he leaves Piers accompanies him because Karst and Agatio are untrustworthy and may be dangerous. As Jenna, Sheba, and Kraden remain behind to tend to Isaac's group, Felix and Piers go up to the aerie of Jupiter Lighthouse and cast the Jupiter Star into Jupiter Lighthouse's well, which spectacularly establishes the Jupiter Beacon.
As soon as Jupiter Lighthouse is lit, Karst and Agatio announce that they have no trust nor further use for traitors like Felix. First, Karst states that the last lighthouse, Mars Lighthouse, is located near their hometown of Prox, and suddenly steals the Mars Star from Felix's grasp, explaining that she and Agatio can finish the job of lighting Mars Lighthouse themselves and therefore no longer need Felix. Karst and Agatio taunt Felix by saying that it is time for him to die, even though his parents currently held at Prox - the reason Felix originally went with Saturos on his quest to bring back Alchemy to begin with - would be let free once all four Lighthouses are lit. Karst and Agatio launch an offensive against Felix and Piers with the intent to kill, but suddenly Jenna comes up to the top of the tower, saying she knew something was wrong when Felix didn't come back after the beacon was lit, and joins them battle. Sheba joins in shortly after that for the exact same reasons, and Karst and Agatio must contend with four separate Adepts at once.
What happens after the battle varies depending on whether Felix's party wins or loses their fight against Karst and Agatio. Should Felix's group emerge victorious, Karst and Agatio command them to finish them off as they lie defeated on the ground, posing the hypothetical scenario that if they don't return to Prox either just like Saturos and Menardi won't be returning to Prox, the people of Prox might retaliate and kill Felix and Jenna's parents; the group doubts that, but before they take action Alex steps in. Alex heals Karst and Agatio enough that they can at least stand and walk, reasoning that if Karst and Agatio are not bluffing about Prox, then Felix's quest to win their freedom would be all for naught if he kills them, and also that Felix's only other course of action would be merely to leave them at Jupiter Lighthouse. Since Karst and Agatio now have the Mars Star, and Isaac's group has now recuperated and is also coming up to the lighthouse aerie, Alex easily convinces the Mars Adepts to flee Jupiter Lighthouse with him using the lighthouse's now-operational exterior elevator so that the Mars Adepts can return to Prox and try to light Mars Lighthouse on their own. Isaac's group reaches Felix's just as Alex and the Mars Adepts leave.
Should Felix's group be defeated, the four Adepts lie defeated on the ground, but alive nonetheless; Karst and Agatio remark that Felix's group was surprisingly powerful in battle just like Isaac was, but that Felix deserves death for his treason. Just then, Alex steps in to tell them off for their petty grudges. Karst and Agatio threaten Alex with death as a consequence for his own treason against them when he abandoned them earlier during their battle with Isaac, but Alex simply states that in the wounded condition they are, they are in no condition to fight him as well. The Mars Adepts become aware that Isaac's group has recuperated and is coming up to the Lighthouse aerie, and Alex drives the point home that unless the pair flee right now with him, they won't stand a chance in another battle. Since the Mars Adepts now have the Mars Star they'd need anyway, they begrudgingly agree to follow Alex to the now-functional exterior elevator from the aerie down to Jupiter Lighthouse's base, and flee just as Isaac's group comes across Felix's wounded party members. After expressing frustration at Karst and Agatio's escape, Isaac commands Mia to revive Felix and the others with her healing Psynergy.
After either of the above scenarios transpire, Isaac demands an explanation from Felix as to what is going on, but before the tense interaction blossoms into something outwardly hostile, Ivan proposes that the two parties properly convene and discuss the many important matters in play right now in nearby Contigo. Felix's party members agree and promise to meet him, and Isaac leaves Jupiter Lighthouse with a stern warning to Felix that he cannot just run away again. Felix's party use the elevator to leave Jupiter Lighthouse themselves and head back down to Contigo. Jupiter Lighthouse is now lit, and though Ivan was not specifically the one to light it as per what the prophecy stipulated, he was involved in the events surrounding its activation.
At the end of Golden Sun: The Lost Age, all four Elemental Lighthouse Beacons are lit thanks to the efforts of Felix and Isaac's combined party of adepts at the aerie of Mars Lighthouse, but the entity which had originally tasked Isaac's group to stop Felix from lighting the Lighthouses, the Wise One, had tricked them into slaying the very parents Felix and Jenna had hoped to reunite with, driving the Adepts to grief and anger. Right after the Mars Beacon is lit, however, the Wise One appears in the dreams of Hama, currently located in Contigo, and instructs her to go to Jupiter Lighthouse, where she will be able to commune telepathically with everyone on top of Mars Light through a special effect the Wise One specifically would allow for. Hama does as she is instructed and comes to Jupiter Lighthouse to commune with the Adepts and assure them that though the Adepts appeared to have suffered a great loss, they should not be deceived, for the Wise One has a caring heart. Obviously the Adepts don't buy that, but Hama tells them that the process shared between Jupiter Lighthouse, the other Lighthouses, and Mt. Aleph that brings the force of Alchemy back to the world will soon begin, and the energy involved will likely make all the Lighthouses quite dangerous, so she instructs them to flee from Mars Lighthouse before Hama leaves Jupiter Lighthouse. Then, as though the Lighthouses are linked, they shoot beams of purified energy from their respective beacons and merge them in the airspace above Mt. Aleph, forming the Golden Sun.
Trivia
- The white block that lies on the "balcony trap door" is only required to be dropped on your way back down from the aerie if you do not instead use Retreat to make it to the angel-flanked Cyclone portal that brings you to the west side-tower. If you try to leave the block in place by using the Retreat method to get past it, it will remain in place until it inexplicably disappears once the cutscene with the rival party and the villains takes place in this same area.
- The game will not result in a game over even if, during the two stages of the boss fight where you are fighting with just Felix and Piers and then with Jenna in addition, all of your party members are felled before the next party member drops by as scheduled. The scene will simply transition to the next stage with the next party member joining the "battling party" right away, but with the battle itself starting with the additional party member being the only one currently not downed.
- The lighting of the Jupiter Beacon does not result in either Piers or Sheba getting their PP meters refilled prior to the boss fight that takes place shortly afterward. This is inconsistent with the behavior of the beacons of the Mercury and Venus Lighthouses in the first Golden Sun; Ivan and Mia will get their PP filled shortly before the party finds out the Mercury Beacon has been lit, and Isaac and Garet will get their PP filled when the Venus Beacon is lit between the two final boss fights atop Venus Lighthouse. This may be a development oversight.
