Found in the Road of Sacrifices.
From the Road of Sacrifices bonfire, drop from the ledge behind the first Corvian Storyteller. Continue onward until reaching a bridge with another Storyteller at the end and several Corvians scattered about. Drop by the right side before crossing and to a small ledge below, then follow the narrow path until reaching a cave guarded by two Festering Starved Hounds. The ring can be found on a corpse inside, along with another one that holds the Braille Divine Tome of Carim.
Boosts the power of offensive miracles by 12%.