Slinza, the Spiked Stampede is a rare Legendary Creature — Beast card from Foundations Jumpstart (J25), collector number 55. Current market price: $0.40, TCGplayer market prices via Scryfall.
Beast spells you cast cost {2} less to cast. Each other Beast creature you control enters with an additional +1/+1 counter on it. Whenever Slinza or another creature with power 4 or greater enters, you may pay {1}{R/G}. When you do, Slinza fights target creature you don't control.