The problem is in their Nonsense "Add Spawn" Code which is literally a dice roll any time a monster takes any sort of damage. Ope Reflect physical did 1 point of damage better spawn 6 monsters. *Facepalm*
Because of this, you want to hit the boss as hard and as heavy as you can, while avoiding doing any light damage. Reflect physical to a minimum/none. Magery pets would be a big no no. Summons also not suggested, the small amount of damage they will do isn't worth the risk of spawning more adds. Stick to Flamestrikes and keeping the dark father Corpse skinned on mages, Stick to 100% Fire Pets with Armor Pierce/armor Ignore on Tamers, a duo of Runic Corruption and the Inferno special would do some serious damage, Archers stick to Armor ignore. Onslaught, Discord all beneficial. Even a character just tossing Evil Omen as fast as they can cast it would do wonders. Word of death for the finish.
And if the spawn is getting out of hand, bring one Heavy Hitter with a two handed axe or War Hammer that can clean out all the adds in 1 swing. Putting Aoe's on your pets for the fight is just going to make it spawn more adds. Especially with multiple dark fathers.
Info sounds good, but Beorn with an Undead War Hammer firing FWW was not able to clean out the swarm even with multiple mages healing him. Given the size of our party, I am wondering if we need, say 1 "heavy hitter" for every 4 or 5 tamer/mages/bards?
Are there 2-3 others who would be willing to bring their Sampires/Paladins next time to help test this theory? I think KD's suggestion of cross-healing would work but Sampire/Hybrid builds should work too. Either way, forming up and moving as a core group would focus weapon & AOE damage on the swarm (and weapon damage on the DF).
If we decide to do this, do we need a name for the heavy hitters? Meats? Leroy's? Doom Tanks?
Also, I heard a suggestion that we have a dedicated rez & healer to get fallen players back in the fray. Thoughts?