Gargos, Vicious Watcher is a rare Legendary Creature — Hydra card from Core Set 2020 (M20), collector number 172. Current market price: $1.17 (foil $1.01), TCGplayer market prices via Scryfall.
Vigilance Hydra spells you cast cost {4} less to cast. Whenever a creature you control becomes the target of a spell, Gargos fights up to one target creature you don't control.