The plasma cannon is the big brother of the Imperial plasma gun, a heavy weapon that turns a tank or a Space Marine into a walking sun-thrower. It’s rare, it’s hungry for power, and it hits like a collapsing star.
What it is
It’s a plasma weapon scaled up past the point a normal human can carry. The plasma cannon, sometimes called the heavy plasma gun, fires a glowing bolt of super-heated energy. On impact the bolt reacts with whatever it hits and blooms into spheres of boiling nuclear energy, like tiny suns. That’s why troops nicknamed it the sun gun.
The size and power draw are the reason you mostly see it mounted on vehicles. Space Marines are the big exception, and Devastator Squads can lug one into battle on foot.
Who carries it
Imperial vehicles that can mount a plasma cannon include the Leman Russ Battle Tank, the Sentinel walker, and Dreadnoughts. Space Marine Devastators field it as a heavy weapon, and Chaos Space Marines use their own patterns too.
It’s more than the Imperium. The Tau have their own plasma cannon, and Necromunda’s noble houses build their own variants, which is a good reminder that plasma tech isn’t as exclusive as the Adeptus Mechanicus would like you to think.
- Leman Russ Battle Tank
- Sentinel walker
- Dreadnoughts
- Space Marine Devastator Squads
- Chaos Space Marines
- Necromunda gangs (House Van Saar, House Escher)
Known patterns
There’s no single plasma cannon. Forge worlds and noble houses each stamp out their own version, and the names matter if you’re building a themed army or chasing a specific model.
Some patterns date back to the Great Crusade, while others are Necromunda originals that never left the underhive.
| Pattern | Notes |
|---|---|
| Mk.I Erasmus | Dark Angels example |
| Mk XII Ryza | Ryza forge world build |
| Mk XII Comet | Variant of the Ryza type |
| Mk XIII | Space Wolves use |
| M31 | Chaos Space Marines |
| Mars | In service since the Great Crusade |
| Sol Militaris Helion Fire | Terran duplex magnacore, Legiones Astartes |
| Primus (Supernova) | House Van Saar, Necromunda |
| Sulis | House Escher, Necromunda, aka the Sun Gun |
Why it matters
The plasma cannon is one of the clearest examples of what makes 40k tech feel dangerous. It’s powerful enough to vaporise infantry and crack armour, but it’s also volatile, and that risk is baked into the setting’s identity.
It also sits at a useful crossroads in the lore. It links the humble plasma gun to the Titan-scale plasma weapons, and it shows how the same basic idea gets scaled up, copied, and reinvented across the Imperium, Chaos, the Tau, and even the gangs of Necromunda.
Key facts
- The plasma cannon is a heavy plasma weapon, essentially an upscaled plasma gun.
- It fires super-heated bolts that burst into miniature suns on impact, earning the nickname sun gun.
- It’s mainly vehicle-mounted due to size and power needs, but Space Marine Devastators carry it on foot.
- Common carriers include the Leman Russ, Sentinel, and Dreadnoughts.
- Many patterns exist, from Great Crusade-era Mars and Sol Militaris builds to Necromunda’s Primus and Sulis types.
- The Tau have their own separate plasma cannon.
FAQ
What’s the difference between a plasma gun and a plasma cannon?
The plasma cannon is the larger, heavier version. A plasma gun is man-portable by a single trooper, while a plasma cannon usually needs a vehicle mount or a Space Marine in power armour to carry it.
Why is it called a sun gun?
Because its shots burst into spheres of boiling nuclear energy on impact, which look like miniature suns. The nickname shows up across Imperial and Necromundan sources.
Can normal humans use a plasma cannon?
Not usually on foot. Its size and power demands mean it’s normally vehicle-mounted, though Space Marines in Devastator Squads can carry one.