Forgotten Ancient is a rare Creature — Elemental card from Conspiracy: Take the Crown (CN2), collector number 182. Current market price: $0.67 (foil $4.24), TCGplayer market prices via Scryfall.
Whenever a player casts a spell, you may put a +1/+1 counter on this creature. At the beginning of your upkeep, you may move any number of +1/+1 counters from this creature onto other creatures.