Hello, jut installed Baldur's Gate SoA, then the newest BigPicture, and started a new game. First problem: Ilyich the duergar just won't die. stays as "agonizing" for ever and kills my party one by one.
Same thing happened with my install. I am running just BP and SoA/ToB. I've got a save file if needed. I had encountered Illyich before activating the acorn quest. On the first approach the two duergar near the entrance ran near Ilyich, and the three of them became hostile after a brief conversation. The archers and mage didn't become hostile at all. Illyich remained unkillable.
Ultimately, I used the console to force him to join the party, took the acorns, and than used the console to boot him.