Sirris of the Sunless Realms

After obtaining the Dreamchasers Ashes in Farron Keep, speak to the NPC (non-player character — anyone the game controls, not you) in Firelink Shrine to obtain the “Darkmoon Loyalty” gesture.

After reaching Irithyll of the Boreal Valley, defeat the Sulyvahn Beast on the bridge at the entrance. Cross the bridge and activate the bonfire. Refresh the area and return towards the Catacombs of Carthus side of the bridge to find Sirris’ summon sign. Activating this will summon you to Sirri’s world to defeat Creighton the Wanderer. Speak with her in Firelink Shrine to obtain the Silvercat Ring and Blessed Mail Breaker.

After defeating Aldrich, Devourer of Gods, a unique Budding Green Blossom will appear in the Shrine Maiden’s inventory, indicating Sirris has returned to the Pit of Hollows in Undead Settlement. Travel there, activate the summon sign to aid her in defeating Holy Knight Hodrick. Collect the Sunset Armor Set in the Pit of Hollows. Speak with her in Firelink Shrine; she will pledge her loyalty.

After defeating Lothric and Lorian, return to Hodrick’s grave in Firelink Shrine to obtain the Sunless Talisman. You can also find the Sunset Shield on Hodrick’s grave outside Firelink Shrine, near the Grave Warden overlooking the cliffs edge.