Murder Turret!
Very basic, but it gets the job done. Place it in a group of enemies and watch them disappear! Or add it to a vehicle and watch as you suddenly have nothing blocking your path! (I literally just stuck a bunch of guns on a construct head but it works well. Flamethrowers keep things from getting close and turning it off, lasers constantly keep things stunned and taking damage, cannons give occasional blasts and do AoE. Its all glued together, but it covers it's weaknesses.)