EF_NODRAW prevents any data about an entity from being transmitted to the client, without affecting it on the server. In other words, it makes the entity disappear from the player's view without deleting it.
It is defined as 0x020, or 32.
To use this effect, turn off SmartEdit mode and add the following keyvalue pair to the entity:
Remember that you can set the effects value during runtime using an entity's
AddOutput input with the input value
effects x (x being any summation of effects flags to enable).
Warning: Using the AddOutput functionality for this, the new value may interfere with an entity's simulation functionality.