Did you take a break? Cuz over a year and a half you should be able to get good enough champs that they can nuke him down or have the utility you need.
Use Voodoo to turn his Buffs into poisons, Morningstar's SP2 to inflict more damage for each buff, Mephisto's SP1 to nullify all the buffs, or Mordo's SP2 to inflict damage per buff.
Comments
Voodoo and Morningstar also work a treat
I've done it with 2* Ronan for a laugh but its boring.
5 star morninstar should it though
Send ur roaster. We could suggest you