Gabriel Mandrake

Gabriel Mandrake is the headmaster of the school for Savents, The Anchorage. He is also the head of Nightshade, a group of assassins. He conducted a series of experiments to modify Weirstones with Lilith. They failed to make anything successful(they caused siezures, fits, and other unnormal powers), ending in he blaming Lilith. He has tried to find cures, also failing. He meets up with Lilith, forced by Jonah Kinlock.

Jonah spills the secret to the other savents in the Anchorage that Gabriel was behind their modified weirstones, while not being responsible for the poisoning.

He is dead in The Sorcerer Heir, likely in the same battle as when Alison died.