Whether intentional or accidental, attacking a friendly NPC in can cause inconvenience and may even jeopardize the character's questline. For instance, striking Sorceress Sellen, the Sorcery merchant within Waypoint Ruins, will cause her to disappear. Unfortunately, there is no way to bring her back or do business with her again — except through Atonement.
Absolution, also referred to as Atonement, is a system that grants you a second chance with an angered NPC in calming their seemingly permanent hostility. This feature allows Tarnished to restore their relationship with an NPC and normally continue business or quests as they were before. Accordingly, to de-aggro NPCs, you must visit the Church of Vows.
Sorcerer Sellen is one of the most important NPCs in Elden Ring. Sellen tasks players with finding her physical form imprisoned in Witchbane Ruins.
Anyone who has accidentally attacked an NPC in doesn't get Atonement for free, as the service comes at the cost of a rare item called Celestial Dew. This elixir is a consumable item within the game that is described as a Hidden Tear you can find in the Eternal City. According to the item, drinking a Celestial Dew allows someone to
Once you have a Celestial Dew, you can head to the Church of Vows and interact with the statue on the altar to atone for their sins (speaking to Turtle Pope is optional). This will remove any NPC hostility you have acquired up to this point. Thus, you can continue pursuing their quests and make purchases from shops without worrying about inconvenient aggression.
This landmark sits across the lake from the Raya Lucaria Academy within the region of Liurnia. To see the exact location of the Church of Vows in check out the video from Shark R on YouTube below!
Removing NPC aggression in does not prevent them from becoming violent again if you accidentally attack them a second time. Using the Church of Vows only affects player actions up to that point — it does not allow you to act with impunity
Read more on screenrant.com