The fight is over.
A few days ago, I and the rest of the family were ordered to attend a training course on defeating sorcery. We found some annoying shadow enclave of overly oppressive spellslingers and proceeded to practice trashing their wards and alarms. It was great fun, I have to admit. I shall plan on returning later to investigate the place in more detail.
After the training, we met to plan the assault on the enemy complex. Shortly thereafter we put the plan into action. Random used the Jewel to boost his power and trash defenses. The less martially inclined among concentrated on trashing wards, blocking teleports, and preventing escapes. The bruisers went in in to kill pretty much everyone who offered resistance.
The Adept made a run for it. Random caught him and it wasn't pretty. He is now pinned to the ground, writhing in agony as he is burning away at the same rate he is regenerating. Lots of witnesses are coming to check it out.
There were dragons in the mountain who may be recruitable. I shall seek them out and see if I can enlist them to become allies.