There are many weapons that you use as traps. Mines, Laptop Guns, or Dragons. If you are being chased, the Mines or Laptop Gun is for you. If you use a mine, run through narrow halls. If you run through a large open area, use the Laptop sentry gun.
Dragons are a lot more sneaky.
You can shoot the real dragon into the corner, and place a self-destruct Dragon where the Dragon used to normally respawn. The other players will run by to pick it up, and get killed. The K7 Avengers' threat detector function can detect the fake Dragon. The Proximity and Timed mines also have threat detector. Remote and Proximity mines can be placed under ammo crates or weapons so you may detonate them, when players run over them.