Freestyle 180° or 270° turn.

You'll need to understand well the backhop. It starts the same, with a twist while lifting the front wheel.

My Favourite Move.
Align yourself as close as you can to the fall, the tyres virtually on the edge.
1° Pull on the bars for a backhop, and give a strong twist like trying to look back. Turn Inwards.	2° Once in the air after the impulsion realign the bike and carry on the turn past the re-alignment.	3° Land with the back wheel first, that lets you more flexibility for finishing to a complete turn.
See the move in an animated gif

Just like flying