Fire Emblem Heroes Paralougue 8-3 Quest Axe Unit (Taking the Beachhead)
[Team 1] 4* Cecilia / 4* Xander / 4* Olivia / 4* Anna
[Team 2] 4* Barst / 4* Olivia / 4* Cecilia / 4* Alfonse
I also managed to do it with 4* Stahl / 4* Frobin / 4* olivia / 4* Legion or Barst (but i figured not many people have 4* F Robin)