Kardur, Doomscourge is a uncommon Legendary Creature — Demon Berserker card from Kaldheim (KHM), collector number 324. Current market price: $0.47 (foil $0.59), TCGplayer market prices via Scryfall.
When Kardur enters, until your next turn, creatures your opponents control attack each combat if able and attack a player other than you if able. Whenever an attacking creature dies, each opponent loses 1 life and you gain 1 life.