Aspect of Hydra is a common Instant card from Born of the Gods (BNG), collector number 117. Current market price: $0.27 (foil $1.45), TCGplayer market prices via Scryfall.
Target creature gets +X/+X until end of turn, where X is your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)