Env beam

It creates a visible energy beam running between two entities, in either a line or ring shape.

Usage Notes
The start and end must be point entities with no sprite or model. They cannot be internal entities or any other entity that could remove itself automatically, like. If both the start and end point entities are destroyed in-game, the beam will no longer work. A beam can use itself as a start or end point.

Developers can specify a group of multiple starting/ending entities by giving them the same name. The  will then randomly select one of these entities to use for each strike. If entity names for either points is omitted, a random point on a solid surface within the radius (specified in its Radius property) will be selected for each strike instead. If both points are omitted, the center will be the  entity itself. Such randomized beams do not cause damage.

The beam will always visibly run from start to end, even through solid brushes. The beam's damage will be absorbed by the first solid thing it hits. If Life is greater than 0, the beam will deal this damage only once, while a permanent beam (Life at 0) will inflict damage gradually.