The "Cabal Ritualist(s)" that banish "Ambassador Hellmaw"(First boss) dont move away from the pillars so any ranged class can just range attack them down.
The "Fel Overseer(s)" dont patrol the rooms, they're just standing completely still in certain locations, untill pulled.
Ambassador Hellmaw can be aggroed if you get to close to him even in his banished state, in which he cannot be damaged but he can most certainly damage you.
Grandmaster Vorpil the voidwalkers that he spawn move WAY to fast they're suppose to slowly "walk" towards his present location at the moment they're full on sprinting towards him making them near impossible to kill before they reach him.After u kill all the Ritualists the boss becomes unbanished but starts running around the room in circle