Tezzeret the Schemer

[+1]: Create a colorless artifact token named Etherium Cell with "T, Sacrifice this artifact: Add one mana of any color to your mana pool." [-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."