Snake Cult Initiation is a uncommon Enchantment — Aura card from Future Sight (FUT), collector number 89. Current market price: $0.48 (foil $7.28), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature has poisonous 3. (Whenever it deals combat damage to a player, that player gets three poison counters. A player with ten or more poison counters loses the game.)