Generally speaking, arts with an XS buildup requirement will be on cooldown for a very short amount of time, meaning you should use them frequently. The Buildup Requirement attribute gives you an idea of how much gauge juice you need to fill an art's gauge, ranging from XS to L. Some are simply for support, enhancing your healing abilities, while others execute truly brutal attacks.
Tap the gauge on your bottom screen when it's full to execute the move. Each has a gauge that fills as you battle. Think of these as your special attacks in a fighting game.
