well Yeti-s do some sort of slam move to Karryn in my current run that gives her disbalanced status for at least 3 moves. that kinda sucks. but otherwise, yeah, werewolves are not really an issue with high enough agility and counter ability.For me personally, Level 4 is much easier compared to Level 3. Werewolfs and Yetis aren't a Threat at all, since you can oneshot Werewolfs and with enough AGI, Yetis will never even hit you. The only new thing that is dangerous are Lizards calling for reinforcements but at this point you should have stuff like Skewer and Cleave to quickly take care of them. Maybe I was just lucky in my last fighter run, maybe I will try one again these days.
I haven't really tried fighting past Noinim, so can't comment, but Aron in lvl 3 is a bit difficult if he has 3 other lizards with him. still manageable in a fighter build with cleave attack.
I usually tend to finish up until the penultimate level of a release (lvl 3 for the current release) as early as I can...in the current run, it took about 8 days with a slut lvl of around 50. Although that's in Secretary lvl with edict count per day increased to 4 and base cost of edicts reduced to 50%, a few cheats to reduce Karryn's lvl up rate by half, increase stamina damage 2x and decrease control by 10. also had an intentional battle defeat in lvl 1 on day 1. had a relatively lengthy battle with Aron, so can imagine that to be even more difficult in Prisoner Mode. evey Prisoner Mode run I had done prior to this were slut based