The Heroes Round Table

What are the chances that 2 leadership will have that affect? Or is it just mostly guesswork?

Does Destiny affect the random roll as well? (Says luck?)

So +2 might power, and +2 might defense are fairly clear, as are their magic equivalents, but what about +2 leadership, or destiny, or magic power(dark)? Is there a clear outline of what these things do anywhere? The fan manual had a good talk on the might/magic power ones and their combat effects.....