Panoptic Mirror is a rare Artifact card from Darksteel (DST), collector number 136. Current market price: $26.59 (foil $94.00), TCGplayer market prices via Scryfall.
Imprint — {X}, {T}: You may exile an instant or sorcery card with mana value X from your hand. At the beginning of your upkeep, you may copy a card exiled with this artifact. If you do, you may cast the copy without paying its mana cost.