Medallion of Power

The Medalion of Power is a sigil used by the superhero Ghost Rider.

History
He uses the sigil to transform into his flaming skeleton form. He can also touch it and create a fireball for offensive purposes. He embedded the sigil into his motorcycle to easily get to it.

Background
While the comics call Ghost Rider's sigil the Medallion of Power, neither that term nor sigil was actually used.