Rhenny
Adventurer
DM may have to adjucate tricky illusions with some of the spells in D&D Next. Right now only Phantasmal Force seems like it may require adjucation, but i expect more powerful illusion spells to be published by the time it release.
A (series of) Strenght contest could do it, with each success/failure either increasing or reducing the distance between the two creatures in pursuit.
I agree. Illusions have always been tough in D&D. I find that there is not much difference between minor image and major image, so it is hard to know what can be added to the illusion other than making it larger. Creative players will always attempt to do crazy things with illusion. In some ways I like the openness and in some ways I don't.
So far, DMing Next has been really easy for me. Part of that might be that the game isn't completely finished yet, but part of it is based on fixed values and BA, and the idea that monster math is not necessarily dependent on PC rules.