SO I made my way to a word wall at the top of a mountain, and was confronted with the usual dragon plus a really high level enemy called "Krosis". During the fight he managed to slide off the side of the mountain and, figuring that hewasn't gong anywhere, I decided to take out the dragon first
After I killed it, I went to take on Krosis, but he was gone.

Does anyone know who or what he is and whatyou get for killing him? Will he reappear at the word wall if I come back later?

He is a unique named Dragon Priest that doesn't respawn. He has a unique mask, as do all the named Dragon Priests. There is a possibility he will reset to his initial location if you leave the cell for a long period of time. If he doesn't though then you missed out on this unique item. Although I would question how good it is..

Krosis-
Lockpicking, Archery and Alchemy are 20% better.


Other Dragon Priests have much better masks.

Ugh, I'm battling it right now and needed a break. That svcker is ridiculous. I focused on conjuration because I hate the spell aiming in TES. That ghost flies around like crazy and his attacks blur the screen, so I have a hard time even hiting it. There's almost no way to dodge his aoe attack, he must've either very high health or magic defense or both and on top of it IT FREAKING TURNS MY FREAKING SUMMONS AGAINST ME?! Also, the dragon shouts I could use don't affect it, great.

I have no problem staying alive and hurting it a little from time to time, slowly wearing down its health, but I swear, if it turns out it starts healing itself, the game will fly out of the window. (On a sidenote, don't enemies ever run out on magicka?)

I haven't found a better mask. For light armor, it has really decent AR, plus the enchants are sweet too especially if you happen to use all those skills.

Ah, it finally stopped casting those fire (?) balls and resorted to ice darts, it was much easier then.

But ... during the battle, someone yelled: "Hey trollface!" WTH? It even appeared as subtitles. Who was that?