As you see in the diagram, a high forward is set up to defend against the power play quarterback, another forward and a d-man take the guys atop the circles and a low d-man covers the slot.
Depending on the puck movement, penalty killers will either go on attack mode or the opposite will happen and have the Diamond collapse into the slot and cede the blueline.

Aggressively attacking the three high shooters can be very effective. The idea is less about trying to score shorthanded goals, but more about disrupting teams from getting into formation.