I found Krosis at a low level and I couldn't fight him at that point so I left him there. I came back at level 17 to try again but he started searching for me because I forgot to sneak at first when approaching him. My horse, as all horses do, immediately rushed to defend me from this horific threat. I tried fast travelling to de-agro the horse but I didn't work so I decide to let my horse die so it could learn it lesson then reload after. What actually happened was much funnier. Krosis just stared at my horse while it kicked him in the face. It was as if Krosis had no clue what was happening, he just floated around and took it. He just kept floating all the way down to Korvanjund where he was finally killed by the bandits down there.
Best 1000 gold I've ever spent!