Yes, I would start leveling to 3.70, before leveling duplicate Caedmon/LJ/Tibertus/Sonya/Li/Chao/Grimm/Kashh.
IMO Prisca is underwhelming even with the costume (I’m not sure, just theory though).
Renfeld is also not so good, but Costume Renfeld is great like mini Onatel, Gill-Ra is good for tourney not for event.
Here is a good way to priority which mana troop to level depend on our roster.
Here is also great troop guide: Troop Guide and Levelling Suggestions
TDLR; what I did for event/turney:
2* troop on each color:
- 1x lvl 4 defense troop (def +11%) for tank turney
- 1x lvl 4 attack troop (att +12%)
- 4x lvl 2 attack troop (att +11%)
So this way, we can easier and almost auto select troop for turney/event, because leveled troop on the top.
3* troop, I’m not leveling if there are 4* troop on color as I think it need more resources, and somehow we usually have some leveled since waiting 4* troop.
4* troop, I priorities mana to level 11 for very fast heroes, and level 5 for costume avarage heroes. And level 23 for long-term.