Heart of the Night

Hmm, how do I win this battle? I've defeated all the original units, but he keeps resurrecting them. Is there an ending? And for some reason, I can't cast regeneration on the summoned dragon.

Keep reducing the original units to a low number of hit points, and then eliminate them one by one. He resurrects 30-50% of what was there each time, until only one unit remains. The dragon is specifically designed as an elemental creature so that regeneration cannot be cast on it – otherwise, it would become immortal.