When a wizard named Mendalus develops a spell that summons an obedient woman named Catherine--exactly like any other summoning spell--it creates chaos in the wizard-metropolis of Meltheria, as many interested parties struggle to understand the nature (and legality) of the Catherine spell, while vast fortunes hang in the balance.
The Lord of the Flies, the Muscimancer has studied magics that summon, control and otherwise deal with flies. The Fly Mage is an unwholesome character, also likely to have magics of disease, rot and pestilence up his sleeves. After fighting through his swarms of flies and his loyal acolytes and slaves, the Muscimancer reveals his final power, transforming into a giant half man half fly hybrid. He can fly, acid vomit, as well as continue to use spells, wield weaponry and command his swarms.