Serum Snare is a uncommon Instant card from Phyrexia: All Will Be One (ONE), collector number 68. Current market price: $0.29 (foil $0.34), TCGplayer market prices via Scryfall.
Return target nonland permanent to its owner's hand. If that permanent had mana value 3 or less, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)