Forgotten Ancient is a rare Creature — Elemental card from Archenemy (ARC), collector number 57. Current market price: $0.53, 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.