Side missions also appear at
random intervals and completion of these (most of which consist of guard the NPC or kill the enemies in the vicinity) will fill your
special attack gauge which upon activation not only unleashes a devastating
attack but also partly refills your gas and blade meters.
Sometimes when your characters do zero damage, you are left scratching your head, and it took a group of us a few days to work out that
special attacks weren't
random and that there was a logic behind it!