Knack has a veritable fulham of special moves available for his use once he has absorbed enough Sunstones.
Shockwave[]
Knack can unleash a massive area of effect shockwave by activating his special moves with circle, then hitting circle again. This attack damages enemies in a relatively tight radius, but one-hits most enemies in the game.
Tornado[]
Knack can turn his relics into a massive tornado surrounding his body by activating his special moves with circle, then hitting the square button. In this form (a relatively short time), Knack can move as a tornado, causing massive damage to those in his path.
Ranged Attack[]
Knack can use a ranged attack by pushing circle to enter special moves, then hitting triangle to launch his relics in a ranged attack, capable of targeting multiple enemies at once.