Overcharge is an Upgrade that can be obtained from Ghost Hunter Rowan's Questline. It's activated by either holding down a mouse (PC) or pressing down on a iPhone/iPad (Mobile), a revving sound will then play.
Overcharge instantly vaporizes all Ghosts in a large radius and 25% Battery is drained. When used in other worlds, it will damage the Ghost to 1 Health remaining. Overcharge has a 1 minute cooldown and can be used in any biome. It is has no effect on Mega Bosses and Bosses.