In theory, when you steal a druid idol disguised as a tiefling (using a skill), druids attack tieflings and a bloodbath ensues. Some of the druids attack you as well. In this battle, Zevlor and Kagha die, but, what is most strange, everyone says "we won", druids and tieflings, those who survived.
Exactly the same happened to me and i was not disguised as anything. :-/
I finally finished my evil walkthrough and apparently this "battle" completely broke my game. Minthara approached grove without a cutscene, all survivors suddenly died on their own, and a poisonous fog appeared around druid location. Minthara thought that I killed everyone myself, but it got worse. In the camp, when Mintara attacks me, I can kill everyone but not her, I can't talk to her, but I can't kill her either, because she is constantly healing, and all my companions seem to have stuck "that night", because Astarion keeps telling me "wait for time".
EA nightmare...
