[Dace De'Briago]

As many boost spells as possible. Protection from level drain. Protection from poison scroll on your fighter mage.

Cast timestop (prevents demogorgons summons doing much).

Beat him to death with your fighter/mage.

This is really a hand-to-hand fight, and you really need to get stuck in on him. Use as many boosts as possible.

He will cast death spell to destroy your summons, so not really too much poing having any.

Good luck.