Yampi Desert Cave

Yampi Desert Cave (ヤンピ砂漠地下洞窟, Yanpi Desert's Underground Cave) is an optional dungeon-style location in Golden Sun: The Lost Age. It is a late-game dungeon whose entrance is hidden within the much earlier dungeon-style location of Yampi Desert; the entrance itself can only be reached with the Sand Psynergy found in Gaia Rock, and the actual dungeon can only be entered with the Teleport Psynergy found at the end of the game. It is like the other dungeons Islet Cave, Treasure Isle, and Anemos Inner Sanctum in that it is harder than the proper final dungeon, Mars Lighthouse, it contains an optional "superboss" named Valukar, and the prize for defeating Valukar is the Daedalus summon sequence. Also noteworthy about the cave is that the Venus Djinni Crystal is found here, and that every enemy can drop a valuable item.

Walkthrough
To gain access to Yampi Desert Cave, first you must return to Yampi Desert itself with the Teleport Psynergy in your possession; teleport to Alhafra and enter the desert just down south. At the large, familiar screen of the desert, go to its westernmost end, and use Sand on the leftmost sand river and pass up beyond the rocks and sandfall. The entrance to Yampi Desert Cave is reachable from here at the upper left corner of the area. When you enter it, the first area you get into has no random encounters and a lone chest containing a Water of Life. Beyond it is a large Teleport Circle on the ground; cast Teleport while standing on the circle to appear in the main dungeon area of the cave.

The main area you first enter in forks left, right, and up, but both the left and right forks are quick dead-ends, so only go up. Ignore the doorway you come across and the downstairs stairwell to the right of that, and go northwest, using Sand to pass through a set of three rocks that block your way left. A third doorway blocked by a brittle pillar is at the northwest corner of the area, so use Burst to destroy it and pass to the next room. In the next area, go north, and pass by the downstairs stairwell. When you get to two rollable stone pillars, roll the horizontal pillar down and the vertical pillar right, and head north above that. Roll a third pillar up, then use Sand to pass beyond the pillar's now-current position to reach the doorway at the top. The third cavernous area you come across branches northwest and southeast; take the northwest fork to find an object sticking out of the ground. Use the Scoop Psynergy to retrieve a valuable Mythril Silver item. Take the southeast fork and lead yourself to a downstairs stairwell at the top of the screen. Take note of this paragraph: All the steps outlined here will be repeated much later when it is time to head toward the dungeon boss.

In the new downstairs area you come down to, climb down the ladder and use Sand to bypass the rocks and emerge at the circular sandy tile just below the earth pillar. Use Move to shift the earth pillar's position down one space. Exit off the doorway to the bottom, and in the next room, grab the Dark Matter from the chest off to the left before exiting off the doorway to the bottom. The room you come across has a more complex stone pillar-rolling puzzle with two horizontal pillars below you and two vertical pillars to the left of that. Roll the right horizontal pillar down, roll the left horizontal pillar up, roll the right horizontal pillar up, and roll the lower vertical pillar right. Now use Sand to transport yourself to the enclosed area just above the right horizontal pillar, then roll the right horizontal pillar down. Use Sand again to transport yourself to the area just above the left horizontal pillar, and roll the left horizontal pillar down. Finally, stand at the tile of sandy ground that pokes out through the corner between the two perpendicular pillars to the left and use Sand to cross over to the other side, and roll the upper left vertical pillar right. Climb up the ladder, enter the elevated door, hop across the brown pillar in the next room, climb down the ladder to the left of that, and use Move on the earth pillar to the left to remotely move it one space left onto the sandy circle. Retrace your steps back to the rolling pillar room, and exit through the doorway at the lower right part of the room. In the next room, go all the way right to find a chest containing an Orihalcon, then climb up the ladder, Burst the brittle pillar, and hop right and go up the upstairs stairwell to return to the first main area of the dungeon.

Now back at the main area you first came across when you teleported into the dungeon, go left past the doorway and Sand your way to the doorway at the upper left corner of the area, and enter it again. Back at the next room which had the two stone pillars, this time go down the downstairs stairwell to the left to get to the room where an earth pillar was shifted one space left onto a sandy circle a short time ago. Go over to an area of sand where a sandy mount appears at four specific tiles of ground in a regular pattern; if you face one of these tiles and wait, and interact with the mound in the short time it appears on that tile, Felix will merely generate a question mark icon. What you are supposed to do is, when the mound appears on the tile you're facing, press the Select button to open the party menu, and cast the Scoop Psynergy (or you could use a shoulder button shortcut to cast Scoop). A Venus Djinni will appear and fight you, and when you fell it, you add the Venus Djinni Crystal to your collection. Now go up, use the Pound Psynergy on the wooden pillar above to get past it, and enter a door to get to an enclosed area where you need to move an earth pillar one space town and two spaces right onto a sandy circle. Retrace your steps back to the two-pillars room.

Back at the room with the two rollable pillars, it is time to head toward the dungeon boss, so now follow the steps of the paragraph that was specifically noted earlier until you climb down the stairwell and return to the room where you had used Sand and then moved an earth pillar one space down. The earth pillar's placement now serves its purpose of letting you hop left across it. Follow the subsequent path through a doorway to get back to the room where you moved an earth pillar one space down and two spaces right; the placement of this pillar now serves its purpose of letting you hop left onto it and hop up from it. Enter the doorway above this pillar to reach the final room of Yampi Desert Cave; if you go up enough, you trigger a scene with a demon-like creature that quickly leads to the boss battle with Valukar. Though Valukar is powerful and has the second highest HP rating of all monsters, it is very easy to turn his tactic of putting your Djinn On Standby so he can use your own summons against you back at him by summoning before he does. After defeating Valukar, interact with the summon tablet he was guarding to gain the Daedalus summon sequence. Yampi Desert Cave is complete, so now Retreat.

Collectibles
Daedalus: This Summon tablet lies at the final room of the dungeon, guarded by the optional boss Valukar. Essentially, the dungeon's "main" goal and reward, following one of the main optional "superboss" battles of the game.

Crystal: This Venus Djinni appears as a brown lump of sand that surfaces at predetermined spots in an area of sand at a regular pattern. To initiate the battle with the Djinni to earn it, bring up your Psynergy menu while the lump appears in the tile right in front of where you are facing, and cast Scoop to scoop up the Djinni out of the ground.

Dark Matter: In a chest immediately visible to the left of the screen when you enter down into a screen from the screen above. Mythril Silver: Visibly half-buried in the ground to the upper left of where you enter one screen in particular. Retrieved with Scoop. Orihalcon: At a chest to the lower right of a screen near an elevated stairwell upstairs. Water of Life: In a chest in the first entrance screen of the cave that is before even the "main dungeon", before the teleport pad.