Abilities (KHBBS)

The Ability system in Kingdom Hearts Birth by Sleep is very similar to that of Kingdom Hearts II, while also drawing inspiration from the Esper/Materia-based systems of the Final Fantasy series. While the abilities present in Kingdom Hearts Birth by Sleep parallel those of earlier games, the system handles active and passive abilities independently—active abilities are handled through the various Command systems, such as the Deck Commands, Finish Commands, Dimension Links, and Command Styles, while passive abilities are treated as in previous games, as a set of abilities on a list that are either turned on or off at the player's will. However, instead of requiring AP rationing to activate abilities, the system in Kingdom Hearts Birth by Sleep has the player attach a set ability to the Deck Commands that they create through the Command Meld process. Each Command recipe has a certain set of abilities that can be attached to the finished product, with the exact ability added depending on the Crystal applied to the ingredients.

Once an ability is attached to a Command, the ability can be equipped by adding that Command to the Command Deck. Until the Command is mastered, the ability will only remain activated whenever the Command is equipped and cannot be used at all otherwise. However, once the Command is mastered, the ability is actually added to the character's permanent list of abilities, can be turned on or off, and will be retained even when the previous Command is discarded. As with the abilities attached to Commands, these permanent abilities require no form of AP to enable. Furthermore, it is possible to acquire multiple copies of most abilities in this manner.

Because all abilities are passive in Kingdom Hearts Birth by Sleep, they are sorted not by whether they are active or passive, but by what type of support they provide. Prize Abilities, produced by Abounding and Hungry Crystals, increase the amount of prizes dropped by slain enemies, or make it easier to pick them up. Status Abilities, produced by Fleeting, Pulsing, Shimmering, or Soothing Crystals, increase the power or effectiveness of the character's various forms of offense or defense. Finally, Support Abilities, produced by Abounding, Pulsing, Soothing, or Wellspring Crystals, provide various perks that cannot be readily categorized.