Sanctum of Stone Fangs is a uncommon Legendary Enchantment — Shrine card from Core Set 2021 (M21), collector number 120. Current market price: $1.08 (foil $4.30), TCGplayer market prices via Scryfall.
At the beginning of your first main phase, each opponent loses X life and you gain X life, where X is the number of Shrines you control.