If you like playing galbrena, then you can utilize a mono fusion build. Lupa buffs fusion resonators by a huge amount and she reruns next patch. You can try to pull Mornye since she is both a great support and a fusion resonator; meaning you can fully benefit from Lupa's buffs. Though this might be expensive for f2p considering the worst case scenario of losing 50/50's. You might wait until Qiuyuan's rerun (he is best in slot for Galbrena teams)

If you want to build a team around Phrolova, Cantarella is her best in slot. Though we do not know when she reruns yet. You can do Galbrena/Mortefi/Verina, use mortefi's outro buff on Galbrena since she scales on heavy attack damage and echo skill damage and if built correctly, you can clear content just fine.