Experiment One is a uncommon Creature — Human Ooze card from The List (PLST), collector number C15-184. Current market price: $0.31, TCGplayer market prices via Scryfall.
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.) Remove two +1/+1 counters from this creature: Regenerate it. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)