A expect on rates in the dark age of humanity created the only chaos god not make by the Eldar the grate horned rat who created his children the skaven with the other rats use as test subjects in the extent that made them in shot the science gave rats pycker powers then killed a crap tone at once to replicate the birth of the empire of man and the result was the grate horned rat who kill them at took the other lab rats into the warp developi g them into the skaven the other chaos gose may have unkillable suvents but the grate horned rat has the most suvents the skaven dins cover the warp and are the biggest faction strong holds in it if the scaven could agree on anything and would match on the empire of man and the rest of the galaxy their would only be skaven other then that is Warhammer fantasy skaven your planet is being invaded by these monsters