Well, here is how it works in theory.
I made a gay little paint thingie that probably won't illustrate much unless you use your imagination, but I tried.
Plane A is tooling along when plane B comes up behind him looking to shoot at him.
At around 1,000 yards or so (time 1 in GPT [gay paint thingie]), plane A begins a fairly gentle turn towards plane B. The goal is to get the top of the canopy pointed at plane B. Plane B facilitates this by flying right at Plane A, because he is trying to shoot him.
At around 500-600 yards or so, plane A rolls wings level and begins to move "out of plane", in other words, he pulls up. Plane B will take the shot, and 99% of the time miss. About .5% of the time he will land a hit on plane A. The other .5% of the time he kills plane A (usually this is in a plane with 30mm or Hizookas). The "timing" on this part (time 2 in GPT) varies depending on how fast plane B is closing. Sometimes you won't start your 'break' until he is 300 or 400 yards away, sometimes you will start it much farther away. The timing is everything.. pull up to soon and plane B easily follows, and blows you away.. pull up to late and plane B has already blown you away.
By time 3 in GPT, plane B has missed his shot and is now pulling around for another one. In other words, he is turning towards plane A, after flying behind or underneath him. This is a mistake. Most people in the MA have learned this is a mistake, so it is much harder to get someone to swallow the bait and turn back into you, normally they'll continue their "extension" to the nearest ack or friend for help. Rewind a little... in between time 2 and time 3, plane A is rolling his aircraft to keep an eye on plane B (I usually skip this step, or do it backwards.. I line up the guy with the back of my canopy so he'll fly through the gunsight as he "extends" or turns back into me). Anyway, as plane B pulls back into plane A, he squirts out in front simply because the faster a plane is going, the larger the turning circle is for that plane.
At time 4, the hapless plane B has flown right in front of plane A. If plane A's pilot has good aim, or Hizookas, or both, plane B is as dead as dog****.
That, in a nutshell, is Leviathn's "magic move".
Get him to take you to the DA and bounce him a few times with film running. Watch the film, then practice it. Note, practicing this move entails flying lower and slower than the enemy planes around you, which is probably why Leviathn is the only one left that uses this move. The rest of us have got disgusted and quit, and nobody that has been playing for less than 3 years or so actually wants to learn A2A fighting.
gay paint thingie You'll have to use your imagination heavily. This is from a top-down view.. so you obviously can't see the vertical part between time 2 and 3.