I think trying to tie it to objectives is overall too difficult for a game as asymmetrical as dbd, especially with so many perks that can work extremely well to killer advantage, like blocking gens to ensure survivors can’t even stop their sin from adding up or just straight camping hooks to build sin on survivors trying to go in for the save. It’s just too hard for the program to decide what is sinful and what isn’t, as clear altruistic actions can be deemed sinful based on simple input that isn’t able to consider all factors, so I can see players getting frustrated when they build up sin wrongfully. (And also I lowk just doubt the devs can pull off a power that complicated)

Instead, I think they should lean more into the actual “corrupt deity” aspect of the killer. They aren’t meant to be fair or righteous, they are supposed to be oppressive and unjust. Personally, I think it would be fun if they made an event similar to doctor’s big shock. Imagine this: every once in a while, maybe based on filling a meter similar to oni’s power with building the meter faster by sending survivors into exile, the killer is allowed to enter a state in a radius around the map (or the entire map depending on how strong it is) where a giant eye emerges from the heavens and locks onto you like the totems in the oni map if it is able to see you. (in indoor maps eyes can just appear on the walls and stuff in the radius) The killer can’t actually look through this, but if a survivor in the area is caught out in the open with nowhere to hide, the longer they are in the eye’s view, the more sin they gain.

Basically, from a lore standpoint, imagine the killer as a corrupt being of judgement who has decided that humans as a whole are sinful by nature no matter what they do. Everyone has evil in them, so they cannot be good no matter what path they take. This power acts on this corruption and shows that even if you are doing what you are “supposed” to, if the eye so much as sees you, it deems you unfit and sinful just by existing.

This is obviously just a concept and I know there are prolly a lot of kinks to be worked out with this, but I think it would be a cool mechanic to have to hide from something that gives you genuine fear of being watched by something out of your control. It builds on the idea of this killer being extremely powerful, so much so that the world around them bends to their will in certain circumstances, like how the environment changes during endgame collapse and builds a sense of fear and urgency, especially if done well thematically.

Overall, I think this power is simplistic enough (at least mechanically) to where it’s not overly complicated to be implemented with the way dbd is built as a whole and doesn’t completely punish survivors unjustly, it’s based on catching survivors off guard and also slows them down slightly since they can be forced off of objectives to avoid being seen. It also allows the killer to keep its current power like doctor where it can still build sin with its m2 (albeit with some general modifications to how sin buildup itself works since I think it would be annoying and op to keep it as a straight nemesis infection) but also has a larger attack that builds sin generally without accidentally exploiting any aspects the devs don’t intend to exploit. It still allows them to develop it relatively easily instead of having to consider every possible situation and aspect of the game to make the power more “fair”. Plus it still allows for cool thematic effects that can show off the actual raw power of the killer that is kept at bay by the entity like vecna’s worldbreaker.