A flashing cut is usually used by post player like the power forward or center to receive the ball in the high post area around the free throw line. The player comes quickly from the block area up to the free throw line to receive the ball with the defender now on his back. This type of cut that involved a quick flash could also bring a guard to catch the ball around the three point line instead of the high post depending on his strengths and weaknesses.
When receiving the pass at the high post, the offensive player has multiple options. If they are quicker than their defender, they can drive to the rim for an easy basket. Also, the offensive player could shoot or back the defender back into the post giving him the upper hand. Or, if he/she passes out, they can dive back into the post to receive the ball back in better positioning.
The main defensive objective is to keep the offensive player in front at all times. They have the upper hand with the option to drive, shoot, or back further down so the defense must stay in front and contest any shot the best way they can without fouling.