I'm not near your level. But after many hours searching I've found that
-------- -------- --------
Sakurai. Sasuke2× earth main
-------- kakashi3×--------
Works the best in terms of combos. Not a fan of Sakurai but she's the only healer I have atmosphere
Combos process from each ability (not heal). However I'm level 37 so don't know what the game play is like at your level.

Auto correct did a number on me there