Font of Agonies is a rare Enchantment card from Ravnica Allegiance Promos (PRNA), collector number 74s. Current market price: — (foil $3.24), TCGplayer market prices via Scryfall.
Whenever you pay life, put that many blood counters on this enchantment. {1}{B}, Remove four blood counters from this enchantment: Destroy target creature.