Horace is the companion of Anri of Astora, an important NPC whose quest line is crucial in achieving the "Usurpation of Fire" Ending.
Upon reaching the Halfway Fortress bonfire in Road of Sacrifices you’ll encounter Horace and Anri of Astora. Speak with them both to exhaust their dialogue and obtain the Blue Sentinels covenant.
After reaching Smouldering Lake:
Enter the side tunnel to the right of the lake’s entrance, where you’ll find he has gone mad and must defeat him.
- 2,000 Souls
- Llwewllyn Shield