Tales of the Teenage Mutant Ninja Turtles #7 (1989)

The Return of Savanti Romero! :  April, Raphand Mike are visting a local history museum and admiring the dinosaur relics, when one of the exhibit's bones begin to swirl and converge - forming the bony but familiar face of Savanti Romero. Savanti explains that he's using sorcery to communicate through the aeons, and that he plans to destroy the Turtles - but he offers them a chance to save themselves - if they'll meet him at the "Ring of Fire." The Turtles are confused as to what this means, but before any explanation is offered, the bones collapse into a heap on the floor.