Helfrost Weaponry are basically reverse Flamers. They are a type of specialized weapon class that is deployed solely by the Space Wolves Space Marine Chapter. These weapons are powered by rare crystals found only in the most remote corners of the Fenrisian wilds. So mass production would be impossible even if they were turned over to the Adeptus Mechanicus. Due to being made from a finite resource. Good thing Space Wolves are Mary Sue enough for adversaries to not take advantage of this via orbital bombardment.
Theoretically, the Cogboys could make versions that are cheaper and more efficient if they felt like it. Maybe even go far as making Lasgun/Boltgun and Hotshot Volley Gun/Storm Bolter equivalents. As Helfrost weapons may be a type of las-weapon. "Laser Cooling," as the name says, utilizes lasers to cool down objects by using photons (aka light particles) to screw around with their atoms. Insert any lame pun as you click the link. Obviously Helfrost weapons are between decades to centuries more advanced than a laser used by an university or government laboratory.
Helfrost Weapons fire a beam of sub-zero energy that can instantly encase enemies in blocks of ice close to absolute zero, colder than the vacuum of space. Unless the foe can move away from the beam or break free quickly if hit by it, they might remain trapped within their glacial tomb forever, or even shattered into a thousand bloody ice shards. The beam of energy fired by these weapons can either be a focused beam for use against large single targets, or a dispersed beam (AKA a 'icethrower') effective against groups of enemies.
Example of Helfrost Weaponry at work: https://www.youtube.com/watch?v=LOWiF8VM-Vg
There are currently three known Helfrost weapons.
A Helfrost Pistol is the smallest, man-portable version of the specialized Helfrost Weapons. Helfrost Pistols are weapons used by the Space Wolves ground forces but is more commonly seen among Iron Priests and project a short-range but devastatingly effective beam of sub-zero energy at its target.
Flesh hit by the beams blacken with catastrophic frostbite. Armour and weapons buckle and crack. Soon enough, unless the victim can fight their way free, they are entombed forever as a withered mummy in a jagged tomb of ice Han Solo style. Its a shame it doesn't come in rifle form...yet. Wouldn't it be cool to have an army of reverse Sisters of Battle/Salamanders?
In 8th and 9th Edition, the Helfrost Pistol, has been nerfed and therefore, is not quite as absurdly powerful as it used to be. It is basically an Inferno Pistol that deals Mortal-on-6 instead of the Melta at a 2 pt discount. Nevertheless, this Iron Priest-exclusive pistol still packs quite a punch, at double the range of an Inferno pistol.
The Helfrost Cannon is a large weapon of the specialized Helfrost Weapons type that is deployed solely by the Space Wolves Space Marine Chapter that is obviously an enlarged Helfrost Pistol given growth hormones and protein shakes. These big guns work on the same way; being powered by rare crystals found only in the most remote corners of the Fenrisian wilds. of course, given the size of these guns, it is unsurprising that these crystals mined must be of such size and therefore, of such rarity that it would most likely be worth more than gold.
The Helfrost Cannon is only mounted on Space Wolf vehicles like the Stormwolf, Stormfang and Dreadnoughts due to its large size, and the weapon can fire either a focused beam against large single targets, or a dispersed beam at groups of enemies.
A Twin-linked version of the Helfrost Cannon can be found on a unique and special Space Wolf Land Raider called the Wrath of Mjalnar and in earlier times exclusively only on the Stormwolf. Double Helfrost cannons, for twice the frosty power.
Lets kick some Ice! BLAM! Referencing Batman and Robin is MOTHERFUCKING HERESY!
In 8th and 9th Edition, the Helfrost Cannon was hit with the proverbial nerf bat. Dispersed, it's worse than the plasma cannon. Focused, it's worse than the lascannon. Just take one or the other, and you'll have a much better life.
The Helfrost Destructor is the largest of the specialised Helfrost Weapons that are deployed solely by the Space Wolves Space Marine Chapter. The Helfrost Destructor is only mounted on Stormfang Gunships, one of the worst looking piece of Imperial Avionics EVER. The weapon can fire either a focused beam against large single targets, or a dispersed beam at groups of enemies like all other Helfrost weapons.
Other than the above mentioned twin-linked variety of the Helfrost Cannon mounted on the special Furry Land Raider. The Helfrost Destructor remains one of the most potent Helfrost weapons and anti-infantry weapons of the Yiffers in Space. Which is kind of needed due to the (un)surprising lack of flamers or meltas compared to other Space Marine chapters.
Tabletop wise, Helfrost Destructor lets it shoot once more on Focused mode and D3 more times on Dispersed mode. Dispersed mode is also D2, unlike regular Helfrost Cannons which gives it huge wound potential against heavier infantry.
Tl;dr, much better than the Helfrost Cannon, so take it.