Altmiller Cave

Altmiller Cave is a dungeon-style location in Golden Sun. It is located northwest of Tolbi and the Karagol Sea, and is explored because the lord of Tolbi, Babi, has gone missing there by the time Isaac's party arrives from across the Karagol. The dungeon features a unique darkness gimmick in which in some rooms, areas beyond the radius of light of torches are pitch black, and you have your own small aura of visibility. After finding and going through the cutscenes inside the cave, the stage becomes set for your participation in the Colosso Finals in Tolbi.

Walkthrough
Enter Altmiller Cave, and let the linear path lead you; along the way, the general area gradually becomes darker while a small aura of visibility remains bright around Isaac; in all the dark areas to come, this represents and serves as your personal field of sight, and essentially means that to find out-of-way passages in this dungeon, you'd have to hug walls a lot, or cast the Reveal Psynergy a lot. Enter the door at the end of the counterclockwise path, and go down the stairs in the next room - you'll see how having your vision handicapped like this can make simple rock mazes more bothersome. In the dark floor below, interact with the chest to the lower right to battle it as a Mimic, which yields a Water of Life upon defeat. Go left and up along this room until you get to an odd white shape on the ground, and interacting with it leads to a lengthy cutscene that essentially describes the puzzle at the end of the dungeon. After you regain control, go down the stairs.

In the next dark floor, go left, then go up to find a hidden path that linearly leads you to a chest containing a vial. Return to where you were, and now you just need to walk along the perimeter wall of the entire room counterclockwise to eventually get to a stairwell leading down. The next room is lit up, so go up and climb up a stairway to a rolling pillar puzzle near a visible Jupiter Djinni. Roll the vertical pillar left, roll the lower horizontal pillar up, cast Frost on the puddle, go up and roll the lower horizontal pillar back down so that it stops at the frozen pillar of ice, then go down around and pusl the vertical pillar left, and push the upper horizontal pillar down to access the Djinni. Save before you attempt to battle and earn it. After earning the Jupiter Djinni Squall, go back southeast and push the earth pillar one space right, so you can go downstairs to the floor below.

In the next large dark room, hug the area's perimeter wall and go along it counterclockwise, and you'll get to a chest containing a Cookie. Return to where you entered the room, and now go along the area's perimeter clockwise until you get to the area where the lower-leftmost lit torch area is, and from there, go to the upper right and you'll be linearly lead to the stairwell going down at the west end of the area. In the next lit-up area you get to, ignore the rollable pillars and go down, and climb up the stairway going left and go along the elevated perimeter of the room counterclockwise. Slide down a cliff slide and enter the door between two blazing torches.

You are in the room with five rocks that the cutscene from earlier described. If you cast Reveal here, you'll see that the rocks are lit up with five colors, which from left to right are blue, green, white, yellow, and red. Interact with and spin the two rocks at the opposite ends of the arrangement to cause some sort of spherical mechanism to manifest on the wall, which will now spin. Now, when it stops, the sphere that is pulsating on the top tells you which color of rock you're supposed to spin. Get it wrong and you'll have to switch the leftmost and rightmost rocks again. Get it right twice in a row (the colors you're to spin the rocks in accordance to are different each time, determined randomly) to open a door to a room that contains a chest, which contains the important Mystic Draught item. Give this to the white outline you encountered earlier (use Retreat and go into the dungeon again to get to it more easily), and the dungeon is complete with another cutscene. Now you're to return to Tolbi and compete in the Colosso Finals.

Collectibles
Squall: Found and fought in an illuminated later room in the cave, reachable by solving a pillar-rolling puzzle.

Cookie: In a chest in the darkened floor following the illuminated room with Squall, requiring manual exploration to reach. Mystic Draught: The key item at the end of the cave, obtained after a color-light-sequence puzzle. Give it to the shadowy figure from earlier on to progress. Vial: In a darkened floor of the cave, in a chest whose pathway to it is totally obscured by darkness and needs to be explored with Isaac's own field of vision.

Story
Deep in this cave west of the Karagol Sea lies a mysterious set of mechanics constructed into the cave by what Babi describes as "an ancient civilization, long since vanished", which may be used as a vault of sorts by Adepts who know how to spin the rocks involved. Other than this, this merely a monster-filled cave. When Babi returned from the Adept city of Lemuria over a century ago, he brought with him a supply of life-extending draught, which he consumed throughout the years to extend his life far beyond its natural expectancy. Babi chose to hide his precious draught within the "vault" in the depths of Altmiller; it was a perfect hiding place because of the cave's darkness and the monsters within, which would keep out anybody else but Babi. Babi himself had a Psynergy-bestowing item named the Cloak Ball, which provides an Adept the ability to visually disappear in places of darkness and therefore avoid detection from people and monsters alike. As Iodem, Babi's effective second-in-command and chief minister in Tolbi, would explain in puzzlement to those he talked with, at times he would secretly tail Babi during Babi's unexplained trips into Altmiller Cave, where Babi would appear to vanish right before his eyes into the darkness.

At the time of Golden Sun, precious little draught remains in the cave, and Babi knows all too well this means his extended life is running out. He has recently attempted to ration the draught between longer sessions, but as a result of waiting too long between drinks, during his latest trip into Altmiller Cave he collapses and remains unable to move for well over a day, all the while kept under the constant cloaking effect of his Cloak Ball. The state of worry that Iodem and the higher-ups in Tolbi's military develop by the second day coincides with the arrival of the traveling Adepts led by Isaac. Isaac's party, upon hearing the rumors of the town ruler's disappearance, decide to help out by investigating Altmiller Cave themselves.

As they are Adepts, Isaac & Co. are able to perceive Babi's cloaked form on the ground in the cave, to Babi's considerable surprise. Unable to reveal himself until after he has drunk his draught, Babi directs the Adepts to fetch the remainder of the fluid for him. After they do so, Babi regains the strength to reveal himself and introduce himself, and momentarily thinks the Adepts are Lemurians. As Babi starts to explain his full story, search-party soldiers from Tolbi arrive and discover them. Babi, thankful to the Adepts for saving him and wishing to speak with them further, enters Isaac in his Colosso competition of warriors so as to observe Isaac's abilities as a warrior and Adept in full. Babi leaves with his soldiers to return to Tolbi, and Isaac's party follows suit.