Hydra's Growth is a uncommon Enchantment — Aura card from The List (PLST), collector number THB-172. Current market price: $1.23, TCGplayer market prices via Scryfall.
Enchant creature When this Aura enters, put a +1/+1 counter on enchanted creature. At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.