Proton Backpack

 is a gun that fires a slow, homing laser stream. It locks onto enemies once it hits.

Trivia

 * This gun is a reference to the anti-ghost weapon from the movie Ghostbusters.
 * The tagline is a reference to the one of the movie's most famous phrases, "Don't cross the streams".
 * The "something strange" mentioned in the Ammonomicon entry is a nod to the Ghostbusters theme song which asks, "When there's something strange in the neighborhood, who ya gonna call?"
 * The "team of investigators" is presumed to have been the Ghostbusters themselves.
 * The is most likely a reference to the Wunderwaffe DG-2 from the Call of Duty Franchise.
 * The shape of the Proton Backpack in the Is similar to the shape of the Blood launcher from Nuclear throne