- Dropped by dark spirit Knight Slayer Tsorig. From the Catacombs of Carthus bonfire, head downstairs and enter the first doorway on the right, where an Ember can be found at the end. Tsorig will invade as the player makes their way out.
- If the player did not defeat Tsorig in the catacombs, he will drop the ring in this location. He awaits hidden near the lowermost staircase of the level, which leads to a lava pool.
When worn, the Knight Slayer's Ring increases stamina damage dealt to blocking opponents by 10%. This makes the player more effective at breaking enemy guards, and also makes it harder for opponents to retaliate due to the stamina drain.