Mirror-Mad Phantasm

A 5/1 flier whose activated ability is a riddle wrapped around its own name. Pay one and a blue, and the Phantasm shuffles itself into your library, then you reveal cards from the top until you hit a card named Mirror-Mad Phantasm; everything above it goes to the graveyard, and that card returns to the battlefield. With a single copy in the deck, this is a self-randomizing dig: the Phantasm you just shuffled in lands somewhere unknown, so the activation mills a random slice of your library (averaging about half) on its way to fishing itself back out. That is mostly a bizarre, repeatable graveyard-feeder. The combo the design quietly invites is the one where you make a token copy or a clone of the Phantasm and then activate the token's ability: with zero cards named Mirror-Mad Phantasm left in the library, the reveal never finds a match, and the entire deck pours into the graveyard. The naming clause is the whole engine. Activate the original and you reshuffle-and-dig; activate a copy with no original left to find and you self-mill out completely. The body itself is a glass cannon, five evasive power on one toughness, but it is almost incidental: the reason anyone runs this Spirit is to weaponize a search condition that points at its own name, which is either a harmless shuffle or a way to delete your library, depending entirely on how many of them are left to find.