Question: If you miss some bosses on previous maps, you cant get them after for achievements?

Well I had to go back to Kingsmouth because i’ve noticed on achievements that i missed 2 bosses. I killed them, but they didnt upgraded on achievement… and the skull that marks them was grey… so… how can I get the achievement?


Which champions?

One is the Feigr Jotun and the other is Forgotten Fiend.