Hydroid Krasis is a rare Creature — Jellyfish Hydra Beast card from Modern Horizons 3 Commander (M3C), collector number 266. Current market price: $0.32, TCGplayer market prices via Scryfall.
When you cast this spell, you gain half X life and draw half X cards. Round down each time. Flying, trample This creature enters with X +1/+1 counters on it.