Quote Originally Posted by masteraleph View Post
A9: They do not interact. Defensive Aura provides a power bonus but is not a power.
If Mark of Warding were less fantastic of a feat otherwise, I'd recommend asking your DM if he'd allow it -- as a conditional +1 to defenses is not even a very powerful feat. But the real meat of the feat is enhancing your mark penalty from -2 to -3, and that's already incredibly powerful, before the secondary bonuses are involved.

It's still maybe worth asking, if your DM is often generous with readings -- but Aleph is correct in terms of the rules as they're written.