Main roles for now :
Main Damage Dealer
Resonance Skill DMG
Havoc Amp
Heavy Attack Amp

Fit nicely with Cantarella and Roccia
Based on current info, other options to buff Phrolova than Cantarella are Taoqi, Zhezhi, Brant, Lumi
Heavy attackers that can benefit from Heavy buff are Jiyan, Jianxin, Zani. Feebs can benefit a little too but probably too janky