Karstaag actually broke my save and I'm not even mad about it

[WhiterunModder]

I went into that fight thinking it'd be like any other Daedric prince summon, right? Wrong. Completely wrong. My level 42 warrior got absolutely deleted in like 20 seconds and when I reloaded, half my quest markers were gone and my follower (Vilkas) won't talk to me anymore. He just stands there. We're married and he's just standing in our house staring at the wall.

Did I corrupt something or is this a known bug? I'm on PC with a pretty heavy mod load (mostly quest and combat stuff, nothing crazy) so I'm wondering if it's a mod conflict or if Karstaag is just genuinely broken in certain setups. The fight itself felt... off? Like the difficulty spike wasn't even the problem, it's that the arena felt like it was lagging or something. Frost effects everywhere, my character kept getting stuck in place, couldn't move properly for a few seconds at a time.

Should I just console command him dead and move on or is there a fix? I don't want to lose my save over this, I'm like 80 hours in and this is my favorite character.

 

[RiftenWanderer]

Karstaag's fight is genuinely one of the buggiest encounters in the game, especially on PC with mods. The frost effect spam you're describing - that's real and it tanks performance hard, which might've caused the quest marker issue and follower dialogue corruption. I've seen posts about Vilkas specifically getting stuck after certain scripted events go wrong, and a broken Karstaag fight could definitely trigger that.

The good news is you probably didn't corrupt your save permanently. The bad news is console commands might not fix Vilkas if it's a dialogue flag thing. Before you do anything, try dismissing him and re-recruiting him - sometimes that resets the follower dialogue state. If that doesn't work, there's usually a console command to reset NPC dialogue packages, though I'm blanking on the exact syntax right now.

For Karstaag itself, ngl I'd just console command him dead at this point. 80 hours is too much to risk. Once you do that, check your load order - if you're running a lot of combat mods, one of them might be making the fight even worse than vanilla. Some people disable combat enhancements during that specific quest and turn them back on after.

What quest mods are you running? Might help narrow down if something's conflicting with the Dragonborn questline stuff.