Warren Warleader is a mythic Creature — Rabbit Knight card from Bloomburrow (BLB), collector number 38. Current market price: $2.69 (foil $3.39), TCGplayer market prices via Scryfall.
Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.) Whenever you attack, choose one — • Create a 1/1 white Rabbit creature token that's tapped and attacking. • Attacking creatures you control get +1/+1 until end of turn.