Rawa Rontek Options

This is one of the magic of Java called Rawa Rontek spell of which in this video the master performs a public demonstration of decapitation.

Illusion? or this is the real deal?

You'll just have to watch it to believe it. Watch the first minutes and skip to around 4.50. Not for the faint of heart.
Rawa Rontek

It is faked. Even with a very sharp knife, cutting through the neck vertebrae, the tough fascia and muscles would require a lot of effort. You will notice that the guy's arm muscles weren't flexing or working hard, and he wasn't out of breath. Not to mention that in a real decapitation there would be a geyser of blood shooting out a couple of feet. I would imagine that it was a fake knife, kinda like this fake arrows they used to have to make it look like you have an arrow through the head.