I actually am going to try to do the One Black Dragon only challenge without using halving for as long as I can. I wonder how that will work. If I see that I am getting summarily trounced, then I will change stuff around. I will, of course, keep plenty of runes at the ready to do so
EDIT: I know for a fact that Impy did it, but he is a much better tactician and much more patient and considerate than I am...