Example
Look at the picture.
Red tiles is masked, white tiles is not masked, but animated to be masked when you hit the trigger crate (you'll put triger zone with the same ID on the white tile ofcurse.)

The blue spring is checked on celling, so you bunch down in the trigger crate, lock off the path.
Sinice the server is the first player, he/she will get in the path, while the other players is send down. (They fall.)

I hope this explained.