Thanks so much, your strat helped me clear infernal.
Used almost the same team
- Masked marth (Reciprocal Aid, Luna, Darting Blow 3, Renewal 3, Breath of life 3, spur def 1 seal)
-Sharena (Rally Attack, Luna, Speed +3, no B skill, Fortify def 3, Hp+3 Seal)
-Nino (Draw Back, Draconic Aura, Fury 2, Desperation 3, Hone Attack 3)
-Ninian (Dance, Moonbow, Fury 2, Sword breaker 3, Hone Attack 3, Fortify res 1)
I dont know why my sharena didnt need vantage and managed to survive all of berkut's hits, i think the fortify res seal on masked marth helped with that.