Actually Catapult is far more similar to Dragon Master than Flying. Compared to Flying in regards to Offense Defense Catapult gets both an attack plus and a defense plus. Compared to Dragon master here's something I wrote before for another thread.
Dragon master is right at 5. Catapult is right at 4.
The main differance between the 2 is that while dragonmaster will often give you more tokens it can be stopped by indestrucable walls. The catipult cannot be.
Also in games with more people there are a lot of regions ajacent to the lake. Being adjacent to the lake gives catipult a mini flying ability (I think I read that the lake caounts as a region) whereas dragon has to fight its way around.
So basically you get 2 minor versions of 2 pretty good powers. combined You get the added flexibility of both powers.
The only other power which grants you both movement and Attacking abilities is Underworld but Underworld does not grant a defense boost and is limited to being usable on a few specific regions.