... your character's spell points to drain his/her opponent's hit points, and transfers 30% of the points drained to your character. It requires the caster to have GM in Dark Magic, Expert in Light Magic, and Normal in Elemental Magic.
You can safely clear out the Dragon Caves in Garrotte Gorge even if you have allied with the dragons. The fates of the dragons wandering around inside any of the Dragon Caves is of no concern to any of the named dragons who live in their own little private caves inside the larger caves. In point of fact, if you don't clear out the dragon caves in Garrotte Gorge before the area respawns, you will miss out on some very nice artifacts deep down in there.