Also known under the name of B-Turnaround, that advanced technique consists in switching the direction you are facing just before starting your special attack, usually your Neutral-B. Instead of B-Reverse, here you turn around before starting your special attack. In order to perform a Turnaround-B, you have to move the stick in the opposite direction of the one you are facing just before pressing the special button. Since Smash Ultimate, it is now possible to use that technique on the ground, knowing that it was only possible on the air previously.