Hollow One is a rare Artifact Creature — Golem card from Hour of Devastation (HOU), collector number 163. Current market price: $0.54 (foil $2.35), TCGplayer market prices via Scryfall.
This spell costs {2} less to cast for each card you've cycled or discarded this turn. Cycling {2} ({2}, Discard this card: Draw a card.)