Protean War Engine is a mythic Artifact — Vehicle card from Alchemy: Dominaria (YDMU), collector number 25.
As Protean War Engine enters, draft a card from Protean War Engine's spellbook and exile it. Whenever Protean War Engine becomes crewed, until end of turn, it becomes a copy of the exiled card, except it's a Vehicle artifact in addition to its other types. Crew 3