Xathrid Demon is a mythic Creature — Demon card from Commander 2014 (C14), collector number 170. Current market price: $0.47, TCGplayer market prices via Scryfall.
Flying, trample At the beginning of your upkeep, sacrifice a creature other than this creature, then each opponent loses life equal to the sacrificed creature's power. If you can't sacrifice a creature, tap this creature and you lose 7 life.