If you lead the succubus back to Zandalor, you can talk to him to get healed (though it might take awhile doing so after every hit). You can cast Aura of Command on her deathknight. Blind then Hell Spikes works well, if you have those skills. Survivor's Curse a few times then an elemental attack should be effective. The fireball spell the male wizard starts off with can be cast almost as fast as you can right click and has a bit of a stunning effect, so all you would need is enough restoration potions (depending on her resistances).
Kaan's Mage Guide (spoilers)
Playing a mage character... (spoilers)
