The Chaos Dungeon is always the last in the each set of four Dungeons. It's full of disturbing things such as Demons, tendrils coming out of the floor and more. The color scheme here is purple and black, fitting of chaos.
DemonKnights are above average fighters with decent stats. Like other "Knight Class" enemies, they will ignore the player until attacked and will wander aimlessly about the room.
Demon Mystics are a bit tricky, as they can only be seen if you are near them. They also fire homing orbs, and will teleport about the room.
Demons are just slightly weaker versions of DemonKnights, and have pretty good stats. They will follow the player relentlessly around the room, unlike "Knight Class" enemies.
Fetuses are just big blobs that are quite useless. They have average stats and won't pose much of a threat.
The Demiurge is a pretty complex Boss. The main body doesn't do much unless the two Demiurge Heads are killed. The Heads will fire at a slow rate and it's easy to dodge the shots. When the Heads are killed, an eyeball emerges on the Demiurge, which fires at a medium rate. The Demiurge can also stomp down, pushing back the player. (Not sure if it can actually damage you by doing this)
Looting the DeadEdit
After slaying the Demiurge, you'll enter a room slightly larger than other save rooms before. Inside will be one of two things. One is what seems to be a coffin, and after touching it, it gives you a Red Chest. The other is a ghost will be floating where the coffin used to be, and touching it gives you a Red Chest. The ghost appears after you've broken the coffin once before.