A great trap
A hiding spot on High Ground is right by the Spartan Laser and two fusion coils. There is a "rip" there, so put a grav lift right below the ripped part. Up above, you can put a Sniper Rifle or any other weapon there, put as many fusion coils as you can by the gate and then set its time minimum to 4.

Then get on top of the part that has the rifles, then wait for the other player to cross the fusion coils, then BOOM!