L shape ambush, bad guys are advancing when suddenly the lateral force will pine them down and forbid them from retreating, forcing them to advance into the support fire, freezing them into the kill zone.
Effective if the blocking force has huge firepower and good cover, of course place security groups around.
Difficulty is for the two groups of your guys to not fire at each other. basically the guys on the side are forbidden to fire on their right, their sector is 9H to 0H, this is easily done if they all are right handed.
The blocking force guys have to shoot straight, also have to stand there as long as needed, the most disciplined and capable guys should go there with the firepower.
the L must be at least 90° or you'll have blue on blue casualties.