Many combinations exist but I used this:
Warlock well, Phoenix protocol
SMG (barrier rounds)
Sword with Vorpal Weapon and Boss mod
Hunters are good with tether.
Titan - Smash
Basically cleared 3 heroic rounds with randoms before getting weasel...
I was lock with well, a hunter was with tether and titan usual smash stuff. Only 4 people at 1015-1020 level. To kill the boss, just get the lock well near him and sword the hell out of him. Also, remember that when boss is immune just destroy the blights powering him, you don't need to kill the mini boss to take away the boss shield.
Make sure well and tether are charged so used appropriate exotics.
For warlocks, storm caller and void Walker and not that helpful so use your well to support. Let titans do the killing with supers. BB is also not effective for hunters.
I used recluse but SMG are good in general due to close range battle.