Poisoned-Wind Mortar

The Poisoned-Wind Mortar is a form of light-artillery that allows a small team of Globadiers to lob a much larger payload of poisoned-wind globes at much greater range than a lone globadier could ever hope to achieve. This two-Skaven team requires one of its member to strap on the mortar upon his back while a second Skaven would load the ammuntion inside the mortar itself. Additionally, with some hastily squaled directions, a team of Poisoned-Wind Mortar has the ability to fire their weapon on the go or fire indirectly at the enemy. Such a situation where hurting the enemy without risking their own lives has always an appealing idea to any Skaven.

When in combat, as the bulk of the firing apparatus can be strapped upon a crew member's back, the Weapons team can advance and catch up alongside Skaven infantry blocks, pausing momentarily to lob high-arching shots onto distant targets, before scurrying forward to keep up with the rest of the army.

Source

 * Warhammer Armies: Skaven (7th Edition) -- pg. 60 - 61