Warren Warleader is a common Token Creature — Rabbit Knight card from Bloomburrow Tokens (TBLB), collector number 5. Current market price: $2.90, TCGplayer market prices via Scryfall.
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. (This token's mana cost is {2}{W}{W}.)