Twins of Discord is a rare Creature — Eldrazi card from Modern Horizons 3 Commander (M3C), collector number 37. Current market price: $0.39, TCGplayer market prices via Scryfall.
Whenever you attack, choose odd or even. Creatures with mana value of that quality can't block this turn. (Zero is even.) Each other colorless creature you control has bloodthirst 2. (If an opponent was dealt damage this turn, that creature enters with two additional +1/+1 counters on it.)