Mishra, Claimed by Gix is a mythic Legendary Creature — Phyrexian Human Artificer card from The Brothers' War Promos (PBRO), collector number 216s. Current market price: — (foil $13.02), TCGplayer market prices via Scryfall.
Whenever you attack, each opponent loses X life and you gain X life, where X is the number of attacking creatures. If Mishra, Claimed by Gix and a creature named Phyrexian Dragon Engine are attacking, and you both own and control them, exile them, then meld them into Mishra, Lost to Phyrexia. It enters tapped and attacking.