Board Thread:Questions and Answers/@comment-35400769-20180425055024/@comment-33489892-20180425060131

Well, I usually just level up fighter's abilities using only their corresponding ability cards (when you select an ability to level up and it's shining, it means that you have ability cards that correspond to it) since you'll get a bonus of sorts when you do apply those cards, which seems to level up those abilities faster. Very rarely do I use other ability cards to level up fighter abilities since it will, for the most part, use up those abilities that can be used on fighters who do have those abilities.

And a side note, even if you get abilities to level 75, their full damage won't be reached until your fighter is at level 75.