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.

Melta Weapons emit devastatingly intense but short-ranged blasts of heat which can melt through almost any material. Most types of Melta Weapon like the Meltagun function by inducing highly pressurised gases from an ammunition canister into an unstable sub-molecular state which produces nuclear fusion and directing the resulting energies down the barrel. 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.