I'm kinda stuck on the 7th floor of the abyss. I'm not really sure who to use as a second dps, or how to structure my team. i have every 4 star except sucrose and I have mona and childe.

My current team setup is Overworld - razor 80 c2 mona 70 c0 fischl 70 c0 Diona 50 c1

In the abyss, my team looks something like T1 -> razor Bennet (c0 lv60) xiangling (60) diona (50) T2 -> fischl Mona flex Barbara (50 c1)

Fischl doesn't seem strong enough to carry team two, but neither does mona. I was starting to level up childe, but I wanted to stop here to ask for suggestions.

(Bonus question, when should I start investing heavily on other characters? When I get razor to 90? Everyone else to 80? Etc)

Thanks guys