You already have pretty good heroes at a decent level, try to max Kingston, Red Hood and Leonidas before leveling other heroes.
Try to level different heroes such as Cyprian and Tiburtus: while you have Kunchen to fight holy titans you could use them on epic tier events, class trials and tournaments.
Kunchen + Zimkitha are solid picks for every raiding team, use them everywhere.
Onatel, G. Jackal and Leonidas can help you against purple tanks
Seshat and Proteus can be added to your Kunchen to fight holy tanks
Buddy, Evelyn adn Kingston destroys blue tanks
Red Hood and Wilbur would make a nice combo with Zimkitha but green tanks are not so common (yet)
Kiril, Grimm and Thorne can do nice 3-target damage when comboed.
I can’t give you many suggestions here as defending teams can’t re rerolled but try to use heroes that nullify defender’s strong points, like bringing Kingston while against Khiona for example.
Always bring Wu Kong, Boldtusk/Kiril (depending on titan’s color) and 3 heroes with type advantage, better if with effects that lower the target’s defense like Buddy & Evelyn, G. Jackal, Grimm, Wilbur and Kunchen.
I use minor mana potions, minor healing potions, axes/harpoons and turtle banners