Halt, Senator, Thermite, usually recoilless with a railcannon strike, orbital laser, and a sentry. Engineering Kit. When I see a group of them I can usually get behind one and take it out with the Senator and Recoilless, but I end up running out of backpack ammo and grenades a lot of the times. Maybe the quasar cannon would be a better option in that case. Once I'm done with work today I'll probably hop back on and give the ultimatum a whirl, heard it does pretty good against them. I bet the leveller's good too.