Song of Stupefaction is a common Enchantment — Aura card from The Lost Caverns of Ixalan (LCI), collector number 77. Current market price: $0.11 (foil $0.10), TCGplayer market prices via Scryfall.
Enchant creature or Vehicle When this Aura enters, you may mill two cards. (You may put the top two cards of your library into your graveyard.) Fathomless descent — Enchanted permanent gets -X/-0, where X is the number of permanent cards in your graveyard.