A cutting insult always seems to do the trick when you don't want to deal with customers or pay your taxes, so why shouldn't fighting an evil wizard from the bowels of hell be any different? "Hey, Nancy! Why don't you try to summon yourself up some brains? And I don't mean as a snack for your putrid pets.
"Well, Dorkgun, why don't you make like a tree and go fuck yourself."
You smirk. Hah! If he's this bad at comebacks, this fight should be easier than expected. "Why should I have to fuck myself when I have yo mama?"
"My mama is a demon from the bowels of Hell, but if you reaaaaallly want to fuck her, then by all means, go ahead."
With that, the Infernomancer opens a chasm at your feet and you fall all the way down into the bowels of hell, where you are tortured mercilessly for all eternity. Plus, the Infernomancer's mom is an ugly skank who uses her teeth too much.
YOU HAVE DIED