Tezzeret the Schemer (137) [Aether Revolt]

+1: Create a colorless artifact token named Etherium Cell with "{T}, Sacrifice this token: Add one mana of any color." −2: Target creature gets +X/-X until end of turn, where X is the number of artifacts you control. −7: You get an emblem with "At the beginning of combat on your turn, target artifact you control becomes an artifact creature with base power and toughness 5/5."