Fuel rod gun
Grunty fools only
You can't use this powerful bazooka-like weapon yourself, but you'll see a few Grunts staggering around with it late in the campaign. Amazing what those little legs can manage eh? Grunts can be extremely accurate from long range, which includes the possibility of blasting a hovering Banshee out of the sky; so beware! Amusingly, the weapon explodes a few seconds after you kill its owner, and the blast quite often takes out nearby enemies, who aren't too bright about these things. As such, you can potentially treat this thing as a bomb for you to set off when convenient.