Darksteel Myr is a uncommon Artifact Creature — Myr card from Scars of Mirrodin (SOM), collector number 151. Current market price: $1.06 (foil $6.86), TCGplayer market prices via Scryfall.
Indestructible (Damage and effects that say "destroy" don't destroy this creature. If its toughness is 0 or less, it still dies.)