Heard-smelt Warpstone! Where-where?!
Oh, it's you lot.
Warpstone can cause all manner of mutations and horrific side effects. For those like Clan Moulder who can (sort of ish) control such mutations, they can create anything.
To quote Mordheim:
The value of the wyrdstone shards is not simply the coin that nobles and merchants are willing to pay for them. It is a well-known fact that the stones are rich in magic, and they are said to grant a variety of powers to those that learn to use them. Tales are told among the common folk of stones that caused a certain farmer’s harvest to double, or of the stone that made old Herr Grutenbauer's dog speak like a man. True or not, these tales hint at the powerful and chaotic forces at work in the stones. The most common use for the stones’ magic has to do with the discovery of the famed alchemist van Hoffman of Reikland. It was he who first observed that Wyrdstone can serve as a catalyst in the transmutation of base metals
into gold. This usage of the stones has come to be the primary obsession of those who seek it, for many are willing to pay princely sums for stones that will make them an even larger fortune. Yet there are those who continue to seek the stones for their more arcane uses, and even mercenaries have been known to keep a stone or two that was thought to bring luck, healing, or other magical benefits.
Yet the stones are ultimately the work of Chaos, and those who seek to use them often learn to fear their magic rather than harness it. For every tale of a harvest that doubled, there are two about the harvests that rotted in the field when exposed to the strange glow of the stones; and for every tale of a dog that learned to speak like a man there are darker tales of animals that turned into a gruesome parody of a man-beast. The tales of magical healings are mixed with many of mutation and death brought on by exposure to the stones. Yet greed is the downfall of many in the City of the Damned, and the greed for power is perhaps the greatest of all...
It is possible for a stable(ish) mutation like Skavenkind or Beastmen with another humanified creature like dogs, cats, pigs, e.t.c. Although chances are a whole Clan of such creatures were created by intent from some dark god, daemon, or mastermind (maybe a renegade Skaven from Moulder who retreated to an island where he created a race of human-like animals? Island of Dr Moreakk?)
