Basilisk
The Basilisk is the redoubtable artillery piece of the Imperial Guard.
In other words it's a cardboard tank with a fuckhuge gun.
And if they had bayonets they would be fuckawesome.
Was it mentioned that they have the second longest range of any weapon in the game (20 feet)? The ability to lob a shell that can effectively instagib a table or two away is simply astounding.