The Horus Heresy is a rare Enchantment — Saga card from Warhammer 40,000 Commander (40K), collector number 126. Current market price: $1.38, TCGplayer market prices via Scryfall.
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — For each opponent, gain control of up to one target nonlegendary creature that player controls for as long as this Saga remains on the battlefield. II — Draw a card for each creature you control but don't own. III — Starting with you, each player chooses a creature. Destroy each creature chosen this way.