Shockwave

Weapon Overview
The Shockwave is an Energy-type weapon. Holding down the fire button will charge it up; releasing the fire button then causes the player's ship to generate a rapid circular burst of energy that will destroy all projectiles and damage or destroy any enemies within its radius. The radius of the shockwave burst depends on how much the weapon was charged before releasing.

Although not a very practical weapon for attack, the Shockwave's projectile-cancelling ability makes it invaluable in boss fights, especially the Cruiser and the Carrier.