There we go, thats what you want eh Shamino.
Well, I've told you why thats unnecessary, as Bubba, Gamedev, and CornedBee have. Just to remind you if its accepting all Monsters, then shouldn't all Monsters have this data? Then simply have getters/setters for this data. You shouldn't need anymore than this data in your Render functions.
First solution: but if you do need data some other special subclass has that others dont, then you could just use virtual functions in Monster.
Second solution: I've said this already, but you can just make the function for Render a template so it can accept any class. The thing is that you would have to use an if statement in order to determine its this special subclass - so why not just overload the function for this special subclass instead. Templates are like overloading, so either way works, but templates reduce the amount of code.
Those are the two simple solutions that DO work.