Medieval AU Anon here! I kind of have 2 ideas on the terms of Killer's time loop
First, I was thinking about a classic, groundhog day style loop, just, like, inconveniently long, say 2 months or more, where he learned some patterns and general consequences of his actions, but there's still too much happening and Killer has too little patience to figure it out fully. He went through enough of them to lose any semblance of impulse control he had before getting stuck, but for whatever he learned to not be too useful, because he has to play longterm here, unlike in one day scenario (where i think he'd actually do better). His spawnpoint is set, but I'm not sure if it would be funnier if it was in the middle of some fight, important event/mission or just in his room, but 5 seconds before some disaster.
And second is where there's a global Doomsday type of scenario happening at some point and the universe decided that he's the chosen one, who should stop it, so he loops back to some random point in time prior to it and has to figure out when he is and how the fuck to stop it. The loop is triggered only by death, related or not, to the Doomsday, and I think in this type it would be cool, if he had something like actual save points, and could pick certain moments and places to return to, so he could learn to abuse that system :)
So idk, pick your favorite, i guess
the idea of killer being the reluctant chosen hero to save the world is too funny to pass up i HAVE to pick it lmaooo he'd be the most unscrupulous hero ever like pleaseeeeee
(i think it would be fun if he started as a pessimist, likely due to dust's premonition and influence. he'd just let the world burn for a thousans times before he got sick of it and look for a way to have it progress past the doomsday event lol. he has to rope horror and dust into it too, just because 🙂)