From Lexicanum

A Gauss Cannon is a weapon used by the Necrons, and in particular the Necron Destroyers. They are part of the Gauss Weaponry list and the special Gauss rules apply. It is a larger version of the Gauss Blaster and has four barrels, providing it with an even higher rate of fire and because of its mounting on a heavier base, it has greater power over a greater distance. Also due to its mount it is able to be fired and redeployed very quickly.

Sources

• Codex: Necrons (3rd Edition)

See also

• Gauss Weaponry