Create Flameskull

You take the dead wizard's spellbook, coat it in the powder, and ignite it. After placing the remains in the skull and dripping in the Mercury, it becomes a Flameskull (see Monster Manual for stats), under your command until you take an action that damages it. After that, it has free will and will likely no longer be your ally.

This Flameskull is tied to you as long as it is under your command, it understands your telepathic commands commands, and you take 4d6 Psychic damage whenever it drops to 0 hit points.