I'll be doing extensive beta testing on almost all 10, 25, 10H and 25H bosses that are released on beta, and updating this thread with anything useful I find.
Feel free to contribute with your thoughts and findings on each raid encounter.
Horridon - Testing Cancelled
Council of Elders: I tanked this but DW is definitely optimal since there's a minimum of three targets to cleave. AMS absorbs and prevents the stack of the tank debuff. Only the Frost guy melees. Lots of inturrupts. AMS absorbs the reflected damage. Death's Advance is nice for getting out of sand. Overall a pretty easy fight (we could have killed it but stopped at around 5% to swap some people out) I didn't check if either of the casting bosses abilities are Dark Simable.