Elusive Krasis is a uncommon Creature — Fish Mutant card from Gatecrash (GTC), collector number 160. Current market price: $0.17 (foil $0.50), TCGplayer market prices via Scryfall.
This creature can't be blocked. Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)