Firemaw Kavu is a uncommon Creature — Kavu card from Time Spiral Remastered (TSR), collector number 163. Current market price: $0.25 (foil $0.35), TCGplayer market prices via Scryfall.
Echo {5}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.) When this creature enters, it deals 2 damage to target creature. When this creature leaves the battlefield, it deals 4 damage to target creature.