An stampede of steel awaits at it's impact location.
The train can be used in the same fashion as the Roller, because it works identical to it, except that this weapon also fires additional projectiles, all of them will travel along the ground until hitting a target. Because of this, the train is an very easy to use weapon.
The main caution one shall take is to avoid firing it in an area with several allies, because they may be hit in the process.
Express: Same as the train, but each cart deals additional damage.