Seer's Lantern is a common Artifact card from Oath of the Gatewatch (OGW), collector number 165. Current market price: $0.07 (foil $0.28), TCGplayer market prices via Scryfall.
{T}: Add {C}. {2}, {T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)