[Fantomen]

Nether bolt/nether darts might work If you haven't got the gems or time to make botox bows.

You can also horror mark him with your astral mages while retreating.

You should have hordes of undead horsemen and skeletons, use them to flesh out your skelespam. Combine with ghost grip.

Set up a reverse communion and have them spam smite. Let the masters cast drain life.