That moment would cause any defenseman's eyes to light up. Which I'm sure happened to Kronwall when Voracek skated from the top of the face-off circle to about five feet inside the blue line with his head down. Here's the video.
It is no surprise that Voracek needed help off the ice. Voracek may miss some time because that hit had viscous power and would not surprise me if it leads to a concussion. Kronwall was not penalized on the play and will not face any suspension time because of the hit.
That was hitting 101, shoulder down, elbow tucked and an explosion through the opposing player. It unfortunate for Voracek that he had to be the lab rat for this presentation.