What i think of this:
-The "Martyr" word sounds like someone sacrificing himself for the greater good, but i feel this active is a pure bonus. It's like burrow to some extent. Skybreaker doesn't attack while Martyr'd, but he's on heal mode. I think that should count in the balance.
-Stats are pretty high for this type of creature. Creatures with utility/actives tend to have low-ish stats, especially attack. See Maxwell's Demon, Butterfly Effect, Arctic Squid, every poison applier, and so on.
-PC for air would be good, and makin git subpar like you did makes sense, concept-wise this is fine.
Those were my 2 cents.