Something about lobotomizing Jim Gordon and the Mayor to take over the city. His hideout would have to be an incredibly conspicuous pyramid in which he stores grain, so I guess the theme should lean into that.

“Dr. Pharaoh”, maybe? He dresses like a pharaoh but he has a surgeons mask, stethoscope, and that old timey mirror on a headband. He throws scalpels much like Batman does batarangs, and has goons dressed like Egyptian royal servants who carry him on a palanquin.