Death Baron is a rare Creature — Zombie Wizard card from Shards of Alara (ALA), collector number 70. Current market price: $4.80 (foil $15.15), TCGplayer market prices via Scryfall.
Skeletons you control and other Zombies you control get +1/+1 and have deathtouch. (Any amount of damage they deal to a creature is enough to destroy it.)