I'm obviously unsure whether or not it is a thing already, but I notice a big thing in good action style combat systems is the use of animation cancelling through combos and chaining up abilities, like weaving spells together without casting times. I feel this mechanic is often rewarding for players as it shows abundance of practice, and mastery, and creates a much more fluent and smooth fighting experience
There's a lot of abilities being put into place for this game, but could it be possible to create this sort of thing?