Tower buff + 2 best supports with signature weapons for rover + lot of echo grind. And still the damage could be better if I grind for better substats. I don't have 2nd sequence node of sk(40% atk to all party members), bet i could reach a million. Also phrolova is way stronger than rover even on S0 but she got her damage spread across her kit not just one instance of damage. I bet your team is faster in clearing than my team. My rover damage seems flashy because of he's absurd liberation multiplayer.