Infinite CF and other cool stuff with ToB installed

[Promise]

I've installed ToB but I want to let my party go through SoA first, I'm currently in Ch 6 and have just cleared the guarded compound(I leave most side quests so that Imoen can have a share of exp). When I saw Koshi and co, I run downstairs to lure them one at a time. Koshi persued and got killed, one nice CF. Then I go back upstairs to fight other enemies and I saw Koshi is there! I guess this is a bug and decided to clear the whole floor at once, another CF. When I'm done I saw Koshi yet again at the 1st flooor! Had I the interest to repeat the 'one at a time' tactic, I can get infinite CFs.
I've tried the same on the lich at the city gate, and it works! Now I've got a bunch of wands and rings of invisibility, this had never happened before installing ToB, kinda strange.