Tezzeret the Schemer

[+1]: Create a colorless artifact token named Etherium Cell with "{T}, Sacrifice this artifact: 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."