The Meltagun, also called a "Fusion Gun," "Melter," or "Cooker," is a powerful, short-ranged anti-armour weapon that produces an intense, energetic beam of heat in the tens of thousands of degrees Centigrade.

A Meltagun works by inducing a minute, sub-molecular reaction within a highly-pressurised pyrum-petrol fuel mix located within an ammunition canister, and then projecting the resulting plasma through the canister and from the weapon's barrel as a blast of incredible heat.

Melta Weapon usage is always accompanied by a distinctive hissing sound as the Melta beam boils away the water in the air, then a roaring blast as the beam reduces the target to charred scraps or molten slag. Meltaguns are the premier Imperial anti-armour weapons, and few if any vehicles can withstand their power.