Some of the changes i think that might work
Dark Pact: Destroy a Demon instead of a minion.
Doomguard: Make the charge part of the battlecry.
Spitefull Summoner: Add the minion to your hand instead of actualy summoning it.
Naga Sea Witch, only effects the card you draw.
2
This one on turn 3 is game over - heck, even later as she destroys minion decks *and* spell decks. Never got a win on this one in many attempts, while I have beaten every other boss. This is a very poorly designed boss.