This is a guide for the yellow crystal room at Fort Dragonia in Chrono Cross: The Radical Dreamers Edition.
To deactivate the yellow crystal, head west from the central area with the save crystal.
What to do at the Yellow Crystal Room
After traversing the walkway, you’ll arrive at a circular maze-like area. Follow the maze clockwise, then head north towards the center. You’ll be near the yellow crystal, but you can’t reach it right now, because it’s on elevated ground.
Go around the center towards the north side of the maze, then follow the perimeter anti-clockwise. After a while, you’ll reach some stairs that lead up to elevated ground. Up here, go through the nearby westward exit.
In this yellow-lit room, inspect the terminal at the back. Carefully read the text, especially the part after the room shakes. The terminal will assign parts of a dragon’s body to your three party members.
At first, it’ll be head, tail and body. This means your 1st party member is the head, the 2nd the tail and the 3rd the body. This is the default arrangement, however, and won’t do anything to help you progress.
Regardless, go back to the maze room. North from the west exit is a glowing blue tile–step on this. This will swap your 1st and 2nd party members. Do this once and your party will become tail, head and body. Now press the Select button to cycle your party once. This will change your party to the desired configuration: head, body and tail.
While in this formation, return to the west room and inspect the terminal again. Confirm that your party is in the head, body and tail arrangement. If so, return to the maze after the room shakes. To the right of the stairs, you can now go across to the blue switch. Inspect this to make some stairs appear towards the east.
Press the Select button again. Your party will become body, tail and head. Investigate the terminal again to alter the maze room, then come back to the maze room. Check the nearby stairs. You’ll notice you can’t reach the blue switch. However, you can follow the second-to-last ring north and reach a new chest, containing an Earth Charm.
Guess what? Hit the Select button again and revisit the terminal yet again, in the tail, head and body position, before returning to the maze room. Backtrack towards the entrance of the maze, near the east side. Above the entrance, go up the stairs that appeared earlier. Make your way west towards a chest with an Electro-Bolt Element inside.
Backtrack to the west side of the maze and step on the glowing blue tile. Your party will be in the head, tail and body formation. Next, press Select to cycle your party members. This will create the final interesting configuration: tail, body and head. Use the terminal in the west room and return to the maze room to see the magic…
OK you probably won’t notice anything different. Retrace your steps so you’re back near the entrance of the maze, towards the east. Go up the nearby stairs to the north, then follow the elevated path south. Just before the end, there’s a new bridge that connects to a short path south-east from the yellow crystal. Here, inspect the stone slab, which happens to be a terminal.
Now the central elevated portion with the yellow crystal will drop to the ground. Needless to say, make your way back towards the center of the maze. Then give the yellow crystal a poke. There is no boss fight here, so relax. Once the yellow crystal is powered down, a yellow dragon statue will light up, generating a yellow circle in the central room.
From here, return to the central room and proceed to your next destination.