Experiment Five is a rare Creature — Bear Snake Mutant card from Mystery Booster Playtest Cards 2019 (CMB1), collector number 73. Current market price: $0.50, TCGplayer market prices via Scryfall.
{1}{Z}: Put a +1/+2 counter on Experiment Five. ({Z} is paid with one mana from any source that could produce two or more colors of mana.)