Mindshrieker 
Creature — Spirit Bird
Flying
: Target player mills a card. This creature gets +X/+X until end of turn, where X is the milled card's mana value.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL