Hmmm another one that pops to mind that I’ve made a dozen ways is the Living Dancing Lights(via a body swap method) who uses his own magic body to fuel his power(Spheres of Power Draining Casting, or Tainted Sorcerer, or Body Fuel, or just Spellfire). Is there some form of blood magic or con-based casting in 5e? His powers were largely blasty and general magic manipulation(at the least dispel at the most spell stealing and absorption) in all of his incarnations so that part is pretty easy I feel. But the race and Con base are what concern me.