"Blaze away!"
He sees as fire the one and only lasting human creation, and views it as the only thing above him. Ulgamoth seems to worship fire and claims it to be "purifying," as seen a year after the Zhentarium's attack, he seems to want to become the God of Flames, challenging Imix the Prince of Fire Elementals and Kossith, the god of fire, in a three way war.
He is a Tosculi Warlock, meaning a he is a humanoid moth-man with hell-like abilities, such as literally hurling a target through hell itself, flaming swords, the ability to cast fire-based magical effects, flight or even deceiving others to do his bidding - though he can do much more.