Yeah, the skavenslaves, whilst absolutely terrible fighters, do offer a few advantages. With their multiple shapes, they're extremely resilient against things like fireballs or thunderstrikes, and they can even be used to soak up missile fire. Being size 3 is advantageous for this as it reduces the overall number of hits you have to take, and reduces the options an opposing player has for scripting missile units. And if they can just survive for a couple of rounds of melee with high encumbrance enemy elites, your regular troops can walk in and kill them much more easily than they'd otherwise be able to.
Plus, if you consider that a lot of the best skaven magic/weapons are highly inaccurate... what better to get blown up than some slaves you expected to die anyway! Of course, rats can fill this role as well. They're just not quite as perfect for the job.
Thanks for the guide
