[Beginner's Tutorial] If it's a Black Cat, you gotta slash it at least thrice..

As you progress through the game, you might occasionally encounter enemies whose health bars are colored yellow/red. These enemies have multiple health bars, meaning they won't be completely defeated just by depleting their health once. Simply put, they have phases. There's no way to skip these phases, so keep in mind that any excess damage dealt will be nullified. When their health reaches zero, a "Gauge Burst" will activate on their next turn, applying effects that benefit the enemy or disadvantage your allies. (In some special cases, barrier counts or weakness attributes might also change!) You can check these traits in the menu. Furthermore, when their health is completely depleted, a star will appear above their head, canceling their action. At this point, if an ally successfully hits them with an offensive spell card, that ally will get the used spell card back.