I have Atalanta level 60 awakened to 3 stars, but I also have a level 1 Frigga. Should I replace Atalanta with Frigga or just keep Atalanta in my formation as I have several Atalanta pieces already and limited amount of promote stones?
It depends on your character level and current formation. If you’re already higher than 70 then focus on SSR mercenaries as the end game formation. Honestly, Frigga is the best supporting mercenary for stunning mobs or bosses and it can also tank better than Siegfield.
However, I do not know your current formation line up so I cannot recommend replacing Atalanta since it is best for the Catacombs and Necropolis.