If you want it to work with a normal trigger in MP you'll have to first link the trigger to a mover. The mover need only be an invisible brush that is out of reach of players.
Once again no need for a brush in your mover. An event is enough.
True, I often use a delay as the thing that moves but I still use brushes occasionally so I can see that it actually gets activated.
"The pen is mightier than the sword.. and considerably easier to write with." - Groucho Marx