The discouragement beam emitter fires a Discouragement Beam which can be redirected by a Discouragement Redirection Cube into a sensor or catcher. They need to be powered with redstone and are also able to be configured to damage entities or knock them back. (Aerial Faith Plates). With Optifine mod installed, the beam isn't visible.Lasers going up or down in a 2 block high space cannot damage or knock back entites