Caudice

The Doormatic 4000

In main room doors, it is a good strategy to plant boomers in the crook of the door (right where it closes) because it is impossible to see because the door closes on it, and when it opens the green circle is under the door, also if you wont be there for the ensuing destruction, you can plant a mine in the crook of the door also so whenever someone steps through the door the boomers will go off and have the potential to take out a whole squad (even a few MAXes!).