So I just experienced something most unusual. I'm running a two player party (in multi) with a KenSage (dual at 13) and a SwashbuCleric (dual at 10). I'm quite high level now for the chapter, but I only got to the Eye of the Cult now.
There is the area below the main cult base, if you go down the hole beside the friend of the ex-cultist.
So, after hacking away a few mummies and ghasts, I went in after the ghoul who talks to you. First I wiped the first room, then the room with the talking guy and the "too much smell" monologue (north of it, to the other exit), and finally the room to the west.
Now, in the room to the west, a Lich appeared, and as this isn't quite my first play-through, he caught me quite unaware (I didn't have any spell protections up, nor my simulacrum running). I almost got him, but then his death spell got trough (I think it might have been a finger of death) and my protagonist was slain.
So, I reloaded, re-entered the area with a tad more defences up, summoned the similacrum, and prepared for the fight... and killed a bunch of mummies and ghasts, with no Lich anywhere near.
Is this normal? Do you random encounter liches?
I always thought major encounters are set in stone...