Fanatical Offering is a common Instant card from The Lost Caverns of Ixalan (LCI), collector number 105. Current market price: $1.12 (foil $1.98), TCGplayer market prices via Scryfall.
As an additional cost to cast this spell, sacrifice an artifact or creature. Draw two cards and create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this token: Target creature you control explores. Activate only as a sorcery.")