So what that it looks ridiculous? Skaven vocabulary does not know this word for if it did, the battlefields of Mortal Realms would not be full of balls of death made out of knives, huge rats with brains on their back or statues dragged by 4 clanrats spewing bolts of green death. And for sure, none of the melting corpses (aelven mostly for now) now littering the battlefields thought this vile monstrosity to be ridiculous. Or maybe they did, but not for long.
Having assessed the situation in the Blighted Wilds, Nickit Cravenclaw quickly determined that what is needed for his inevitable ascendancy is firepower. Normal Warp-Lightning Cannon would be an option, sure, but even he thought that it might be a bit unpractical in this landscape filled with vines and undergrowth. Instead, he made his own Warp-Lightning Cannon and mounted it on top of, admittedly quite unfortunate, gnaw-beast, the whole thing far too ridiculously large for it to be carried by the beast for any long period of time. However, that did not matter much to Nickit, for before the beast will die of being overburdened, it will explode anyway. To Nickit, this might even be a way of showing mercy to the beast. Or, more likely, he didn’t really think about it at all. Nor about the other rats destined to die while either shooting the gun or dragging the beast around.
Nickit hopes this creation of his will give him an edge over his enemies (meaning literally everyone) in the coming fights, for what better way to dispose of rivals, then to accidentally hit them with a beam so poverful it vaporizes all it touches. Oh no good sir, my boss-foe Snotsqueek never showed up for the fight in the first place...