No, I dont know what a ferrox is either. In Descent they seem to be blood drinkers or ghouls os similar. They have vesitgial wings under theier arms. As a result I used a vampire figure as their leader. I plan to use these in Fear and Faith and other horror games too.
As with all of the Descent figures, the main priority was to get the whole lot finished to an acceptable standard, not to paint display pieces.