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.
Buuuuuut
After, Astarion says that he is impressed that you killed druids, so apparently tieflings won. Since Kagha is dead, they won't be chased away again.
