How does the Masking shader work?

I were trying to use it to make it look like our character is walking behind something wihtout having to make a seperate object to cover him up.

like He was trying to walk behind a pillar that is built into the map and normally he would just always be ontop of it but I want it to look like he was walking behind it with out using a seperate object to cover him.

Create a transparent block with the mask effect(the mask object essentially sets the alpha of objects behind it to the alpha from the image), stretch it over the pillar, then check the "Force Own Texture" on the layer properties for the layer it's on. Although for this to work right you'll want to put the character and mask effects on a layer above the scenery, otherwise you'll end up erasing everything behind the mask object.

Interesting. I never would have thought you could do that sort of thing.