After you reach St. Tyna's with Anca in The Blood of Dawnwalker and make a safe path for her to the library, you'll discover that Leonica, whom Anca believed to despise magic, fell victim to it. In a moment of desperation, as the covenant fell ill from the plague, Leonica attempted to save the nuns by using Witchcraft to prevent their death.
As is usually the case, the hex didn't work as intended and turned the nuns into lifeless zombies that now haunt the grounds of St. Tyna's. When you find Leonica, she will be attempting to perform another ritual beneath the library, which you'll stop by killing her. Only after she's dead will Anca learn that you both misinterpreted the situation.
As it turns out, despite looking like something straight out of The Nun when you arrived, Leonica still had some semblance of sanity and was actually attempting to reverse the hex she put on everyone to free them before you interrupted her. Now, the ritual is incomplete, and the nuns might be stuck in this state forever.
That is, if Anca doesn't finish the ritual herself. Shortly after finishing off Leonica, Anca will search the room and find the ritual notes. Once she realizes what the ritual was for, Anca will tell Coen she wants to complete it herself as penance for all of this being her fault, in her eyes.
You will have a quicktime decision to make here, but you can pause if you want a moment to think. You cannot save during the conversation, but you should have an autosave after defeating Leonica if you didn't overwrite it with a manual save.
You'll have a moment to decide whether you want to let her go through with it. The different outcomes and options that lead to them are outlined below.
Anca will tell you she needs to complete the ritual.
Anca will convince you that you don't understand and she needs to do this.
سەرچاوەی فەرمی بە زمانی ئینگلیزی: https://www.thegamer.com/the-blood-of-dawnwalker-anca-leonica-ritual-st-tynas-undead-guide/