Having dealt with the gnolls, the party descends into the depths beneath the throne of yeenoghu. They detect some creatures running by below them, and allow them to pass. They proceed into a mossy cave, with Sever in the lead. He encounters a mossy duplicate of himself, and feels lessened somehow. The rest of the party joins him, and they battle duplicates of themselves, who have stolen key abilities from them. The Avengers cannot use their Oaths, the Cleric and Paladin cannot heal, etc. As those creatures fall, a larger amalgam of the duplicates emerges and battles them, using their combined abilities against them. Defeating that creature, they continue on and find odd translucent tendrils on the ground, leading down a passage. More and more of these are found, converging at a point in a large room. It’s filled with thralls, the mind flayer lich they are seeking, and a huge brain in a vat of goo. They party is teleported around the room, beaten and knocked senseless. The brain controls the creatures to do it’s bidding. It’s been cut off from it’s society of thralls and brains, and is using the other creatures to dig it’s way back through a cave in. The party eventually defeats the creature, releasing it’s hold on the others. The Illithid King joins them and they make their way out.