when you're wandering around in refinery, you noticed a Helghast soldier doing push the button open the lift. Then, a Helghast Heavy Trooper named Arc Trooper appeared with his electricity gun. He shot his electricity gun, then he prepared to fight with you. When you shoot the Petrusite cannister from conveyor, it fall to the ground and explode in a wave of electricity near him, causing him to stun, fall bent over, and exhale. He showing you the Petrusite electricity red tanks mounted on his back as his weak spot while saying in deep panicking robotic voice, he wants you to shoot his Petrusite electricity red tanks on his back

Aaaahhh!!! Don't...! Breathe...! Don't...! Move...!