The Knee Slicer from what Scott Sonnon calls the 'Reverse Saddle' is a compression submission on the knee. This is a great technique for submission fighting. The MMA application would depend on your ability to avoid strikes to the head while you are going for the Slicer.
In the video Scott demonstrates how to apply the Knee Slicer from the Reverse Saddle position. You can get to this position a number of ways. You could attack the open guard to get there, pop over from Side Mount, slip under on a leg shot etc ...
Scott also goes over one of the counters to the submission. This is awesome because it actually allows you to improve your position and get to Side Control.
I highly recommend Scott's leg lock DVD. You can check it out by Clicking Here.
