Diggle Nog should activate your diggle form if you have one, but use the generic diggle nog form if you don't have werediggleism. Transformation should be based on how many abilities you have from the werediggle tree: I like 20 rounds + 2 rounds/level. The final ability should permanently make you a diggle, with a transformatory option to return to being human for a short time (basically inverting werediggleism's effects).
