Duty-Bound Dead is a common Creature — Skeleton card from Magic 2013 (M13), collector number 92. Current market price: $0.11 (foil $1.31), TCGplayer market prices via Scryfall.
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) {3}{B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)