Hmm.. thought about this a bit more and I don't like my previous answer, since it's 1) not entirely consistent with how Block and Dodge work now, 2) It would be difficult to show the player when they actually helped.
So instead, what I think I'll do is have Block and Dodge just work normally against attenuated attacks, subject to the same modifier evasion gets based on distance from the blast point. i.e.: If an AE is dropped directly on your head, they don't help at all; at the outermost edge of an AE, you have your normal chances to Block and Dodge.
Lucky Dodge will of course work as it usually does, since Dodge itself would.