Ok so i've played woolhaven. Loved it, Hagar my beloved girlfailure <3 The other lambs were soooo gooood. The NUANCE. The rot being both the literal decay of Yngya's heart but also a metaphor for how holding on to rage like the lambs did can destroy you from the inside out. The recurring themes of damnation and forgiveness, With Hagar trying to atone for her sins and being shunned by the lambs, and the lambs realizing what they've done to Yngya AFTER it's too late, and the only thing they can do is beg for her forgiveness and keep their souls bound to woolhaven instead of moving on or being revived as atonement.
Also, did anyone else notice that woolhaven isn't the first time we've seen rot? Remember how the Bishops looked in their rematch fights? They were all rotten and decaying, because their souls weren't properly put to rest. And we see that this is the same thing that happened to Yngya, but much much worse, probably because she's been trapped in this half-dead state much longer and the rot's effect has been boosted by her disciples ritual. but yeah i just thought that was a cool detail.
Also Marchosias is based as hell. He said he would never bow to a god and he MEANT IT! Honestly hot take but I hope we DON'T get him as a follower ever, it's honestly so much better that no matter what you do he 'wins' by refusing to be converted, even if it means dying. Having him become a follower would be such a disservice to his character.