>>96244900
Honestly, take the bull furnace as a base, make the head area look a bit like this alien from Ben 10, and give it hands or melee weapons for arms, and it's pretty much what I'd envision a "soul furnace" to look like. Make the belly a n open-mouth skull where the corpses or souls are shoved in by the attendants. They even painted it with green balefire colors for some reason.