This really isnt much of an exploit, but i was in blood furnance and i thought i'd show you guys something i found out. If you sap one of the channelers on the last boss (They form a star outa purple lasers or w/e they are) the 1 u sapped will stop channeling to the person its casting from its left hand, Like in this picture.
Although it wont do much, i still wanted to share this.
This also works if u attack them then vanish, and maybe if you shoot them then feign death.