Gabomba Catacombs

The Gabomba Catacombs are the cavernous area underneath the Gabomba Statue in Kibombo, and serve as an optional dungeon in Golden Sun: The Lost Age. The Cyclone Psynergy received in Madra is used here to properly explore the dungeon, and in addition to Mud, a Venus Djinni, the main reward from the dungeon is the Tomegathericon class-changing item.

Walkthrough
The weeds on the floor here are what Cyclone clears. Set Cyclone to a Psynergy Shortcut. Don't use it on either the spiral hole that's already there or the patch of weeds to the top-left. Instead, go around so you're just within range of the weeds inside the rocks, and use Cyclone to descend a level. Here, save your game and fight the Venus Djinni. If it runs, you'll have to leave the cavern and return to the top level so you can get back to it. Defeat Mud to have it join you, then Set it to Felix and give Piers the Mercury Djinni that he had. Slide down the groove, then climb up the ladder and go around the path to the right and exit to the north. Back on this floor, use Cyclone on the top-left weed patch to uncover a Cyclone portal.

Head around the long path to the left and go through the door at the top. In here, use Cyclone on the patch of weeds to uncover a Mint. Head north, descend the ladder, and use Cyclone on the patch of weeds to uncover a puddle. Freeze it with Frost then go back up and jump across. The weeds at the top of the room form the Reveal symbol (you'd be even more puzzled otherwise - using Cyclone uncovers six random puddles). Use Reveal and head down the stairs.

Head left to the river. Ignore the left-hand exit of the river; instead, weave your way in-between the rocks up the river (the path can be a little hard to see) until you can get off further up on the left-hand side. Go down to the weeds and use Cyclone to uncover a puddle. Freeze this, then go back down to the lower left exit of the river. Go up the ladder to the left and hop across to the stairs.

Go down the ladder and use Cyclone on the weeds to uncover a Mad Plant, which attacks you. It's a bit like a Mimic - tougher than an ordinary enemy but not as hard as a boss. Beat it to get a Game Ticket. Climb up the ladder further ahead and you will encounter the GG again. It'll give you the Tomegathericon which is the third class-changing item. Once you've got it, Retreat to the exit and leave Kimbombo.

Collectibles
Mud: When you first enter the Catacombs, cast Cyclone close to the upper-right mass of weeds and you will be transported very near this Djinni in the floor below, where you must then battle it to earn it.

Mint: Found by casting Cyclone on a large, contained mass of weeds. Tomegathericon: The main treasure at the end of the dungeon, gained after a cutscene.

Story
The catacombs underneath the Gabomba Statue are meant to be a test, and thus a sort of rite of passage, for the newly elected Witch Doctor of the nation of Kibombo. At the end of the cavernous area is an idol containing a spiritual entity named the Great Gabomba, and it holds a tome of Witch Doctor magic known as the Tomegathericon, from which the Witch Doctor would learn Psynergy associated with his position.

In the present day and age, that successor to the Witch Doctor is Akafubu, and he has earned the honorifics of his office through a prior ritual which Felix's party of Adepts has secretly assisted. However, before the Great Gabomba could then tell him about the Catacombs and the test he would have to take for the power, Akafubu ran off back outside, all happy about his new position. Felix's party then, at a later date, returns to the statue, enters the Catacombs, and makes it to the end where the idol and the spell book repose. The spirit of the Great Gabomba informs them that they have earned a power that was originally meant for Akafubu, who was plainly ill-prepared for this test; however, it assures the group that it would teach Akafubu the Witch Doctor magic itself should Akafubu make it to the chamber. Felix's group gains the Tomegathericon and leaves.