I dunno... I think this falls in the "too stupid to be in my campaign, but nice try" category.
Not EVERY thread in the rules forum has to devolve into debating very sketchy wording. After all, this is a gaming forum, not a courtroom. Nobody's life is at stake, and nobody's career is hanging on adhering to a specific, standardized enforcement for these "laws".
Besides, x6 power attack damage on one feat is farcically opposed to the usual D&D balance. You may as well start handing out epic feats at 5th level right alongside Leap Attack, then... but when it's your game, that's ok, do as you'd like. We on the ENWorld "D&D Rules" forum pass back and forth our experiences with using the D&D rules so that we can build on each other's successes and have even more fun than otherwise. Blatantly tossing around extreme interpretations and attempting to call them normal doesn't help that goal.
If anyone feels I'm accusing them of something, their guilt is self-evident, but that is not my intent. I'm simply suggesting a certain perspective on why we are here.
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So, I was wondering about a particular application of Leap Attack: Talons. The natural Talon attack deals double damage on a charge in flight, in the DMG flying is considered just another mode of movement that uses the same rules for charging and such as those used on the ground, and Leap Attack is used generically for "combining a jump with a charge". That little string of logic would suggest that you could use Leap Attack while flying, and thinking about the actual physical action of leaping into an attack as a parallel of diving into one suggests the same. However, you can't actually "jump" while flying, lacking a solid support to jump from, so can you even MAKE a jump check?
If a player in a game I was DMing asked me this, I'd say "yeah, sure, make your jump check as though jumping down from at least 10 feet, but if you fail the check you lose the bonus damage, and if you fail by 5 points, you end up prone." I think that's pretty fair, but it's off the cuff, as I don't think I'm seeing any rules to actually SUPPORT that decision.
Thoughts?