Master of Etherium is a rare Artifact Creature — Vedalken Wizard card from Double Masters (2XM), collector number 57. Current market price: $0.70 (foil $1.65), TCGplayer market prices via Scryfall.
Master of Etherium's power and toughness are each equal to the number of artifacts you control. Other artifact creatures you control get +1/+1.