well i already battle krosis and i forgot to get the mask when i came back he was gone and his coffin was closed can you fix this bug and is anybody else receiving this problem I allready know throw voice too what do i do and remember only xbox

It's not a bug. After a certain amount of in game hours, corpses are cleared away, all of them, including any items on them.

It's designed like that so your save game doesn't get bloated by corpses everywhere.

Again, not a bug or a glitch. You just missed out on your chance for it.

Reload a previous save, do it again and take the mask. !!!