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40K Tactics: Raining Hell with the Thunderfire Cannon

7 Minute Read
Jan 14
Today we talk about the Thunderfire Cannon, maybe the greatest support weapon for the Adeptus Astartes.  The Thunderfire Cannon is a Heavy Support choice for the Space Marines. The unit consists of a Thunderfire Cannon and Techmarine Gunner, coming in at a bargain 93 pts for the unit.

Thunderfire Basics

The Thunderfire Cannon is most definitely a Competitive choice. It is common to see at least one, if not more, of these in a tournament Space Marine list. It provides some fantastic long range anti-infantry firepower that can fire at units out of line of sight. It also has access to a couple of very strong stratagems that further boost its utility. Wargear:
  • Thunderfire Cannon- 60″, Heavy 4D3, S5, AP-1, 1 damage. This weapon can target units that are not visible to the bearer.
  • Techmarine Gunner has Flamer, Bolt Pistol, Plasma Cutter and two Servo-arms


The Thunderfire Cannon is a great long-ranged support weapon for a Space Marine army. The range of 60″ means that it can target almost any unit on the battlefield with a central deployment. This provides the Thunderfire Cannon with a huge threat range, so it can contribute its firepower to the battle for every turn that it is functional in most cases . The Thunderfire Cannon gained a number of benefits in the new codex. The first is it went up to BS2+, which is a great boost to its accuracy. In addition, it also went up to a 2+ armour save, further improving its durability. The Cannon has the potential to do between 4-12 shots with one volley, averaging about 8 shots per turn. At S5, it will be wounding most infantry units on a 3+, making it great for taking on weakly armoured infantry, such as Ork Boyz or Guardsmen. On the first turn, with the Devastator Doctrine active, the Thunderfire Cannon will be at AP-2, so will be great for taking one more heavily-armoured infantry or those in cover. It will still be AP-1 if you switch Doctrines, so will be useful for taking on a variety of units after that.
The Techmarine Gunner has some decent firepower with the Flamer and Plasma Cutter, but you generally won’t be getting to use these unless your opponent gets really close. Ideally, you won’t want to have to use his firepower, as you want to keep enemy units away from your Cannons. The Thunderfire Cannon has some decent defence against enemy attacks. At T6, four wounds and a 2+ save, it will take some reasonable firepower to destroy it. However, its best defence is that fact that it does not need line of sight to fire, so you can afford to hide it behind some ruins or in cover, out of sight of the enemy firepower. It will only have to worry about your opponent’s indirect fire in most cases. Another bonus of the Techmarine Gunner is the ability to heal D3 wounds per turn, so you can heal up the Cannon if it takes damage during your turn but is not destroyed. The Thunderfire Cannon is great for taking on enemy units that are holding backfield objectives, potentially hiding out of line of sight or inside a magic box. This also makes it useful for taking out weaker Engineer units that are hiding out of line of sight, stopping your opponent from scoring these points. I also find the Cannon is great for targeting weaker enemy units for scoring First Strike or First Blood. It is great for taking out squads such as Space Marine Scouts, small units of Grots, Astra Militarum Infantry Squads, etc. This can be a nice, easy way to pick up a kill point or First Strike with relative ease.
The Cannon also has access to a couple of great stratagems. The first is Suppression Fire for 2CP. This allows you to fire the Thunderfire Cannon again if it did not move. This doubles the firepower available and can be great if you are only running a single Thunderfire Cannon and need to finish off a key enemy unit in your shooting phase, or if you have a bad roll for the number of shots with your first volley. It is pricey at 2CP, but it has come in very useful for me in a variety of tournament games for ensuring that I score a point or take out a key enemy unit to stop my opponent from scoring. You are less likely to use this if you are running multiple Thunderfire Cannons, but could potentially allow you to fire up to 4 times with three Cannons, and do a lot of damage to enemy units. The other useful stratagem is Tremor Shells, for 1CP, If you use this, you subtract one from the wound rolls. However, if you hit, then the unit that is targeted must halve their movement, advance and charge rolls in their turn (unless they have the Fly or Titanic keywords). This gives you the ability to seriously hinder the movement of a key enemy unit, or stymie an attacking charge in your opponent’s turn. I don’t find that I use this stratagem all too often (I don’t think I have used it in any of my last 10 tournament games), as many of the units you might want to stop have the Fly keyword. However, I think it has the potential to be game winning in many situations. In a game that places a lot of emphasis on moving and grabbing objectives, the ability to restrict your opponent’s moves and deny them a charge or objective-grabbing move is a great tool to have at your disposal. When paired with the great board control units the Marines have access to (Scouts and Infiltrators), this can really allow you to restrict your opponent’s moves. As far as I am aware, you can pair Tremor Shells and Suppression Fire on a single cannon. For 3CP, this allows you to halve the movement of two key enemy units in your turn, a great bonus if you get the first turn. I’ve used this to great effect to restrict the movement of a couple of Lord Discordants or large mobs of Ork Boyz, keeping them from being a big threat to your army for several turns for a reasonable CP output.

Support Units

A Captain or Lieutenant are great support units for a Thunderfire Cannon, allowing you to re-roll 1’s to hit and to wound, respectively. This will help to boost the damage output of your Thunderfire Cannon(s) in the shooting phase. It can also help to have a screening unit for the Cannon to prevent enemy reserves from getting close enough to target the Thunderfire. A unit of Devastators or Intercessors can perform this role, as well as giving you a unit for holding an objective, as well as contributing their firepower to the army.

Chapter Tactics

Iron Hands is obviously a strong Chapter Tactic for the Thunderfire Cannon. This allows you to re-roll 1’s to hit while the Devastator Doctrine is active. Not only does this improve the accuracy of the Cannon, reducing the need for Captain support, but your Thunderfire Cannon will likely be at AP-2 for the whole game, boosting its damage potential further (unless you change Doctrine for some reason). In addition, you get a 6+ save against wounds, giving you a nice durability boost to the unit. While White Scars is not a great Chapter Tactic for the Cannon, it does give you access to the Feinting Withdrawl stratagem. This allows the unit to fall back and still shoot, useful if your Cannon does get tagged in combat but is not destroyed. The Ultramarines Chapter Tactic also allows the unit to fall back and fire, at -1 to hit. While the Tactical Doctrine is active, you can also move and fire without penalty. Less likely to be use, as you probably don’t want to move the cannon far from its starting position, but may be useful every once in a while. Imperial Fists allows you to ignore cover save bonuses on the Cannon. This is very useful, as you are likely to be targeting units in cover or behind cover with the Cannon during many games. With AP-2 and ignoring cover, this can put the hurt on a number of enemy units in the first turn, and subsequent turns. The bonus to damage against Vehicles is only a good bonus if you happen to need to target a vehicle, or are attacking lighter vehicles, such as Venoms or Sentinels. If you are making your own Chapter, then Master Artisans is a great boost for the Cannon. The ability to re-roll a single hit and wound roll is great for boosting the damage capacity of the Thunderfire Cannon.


The Thunderfire Cannon is an incredible fire support unit for the Space Marine army. At only 93 pts, it is an absolute bargain, and it is common to see several cannons in a competitive army. It is able to function without character support in many cases (especially as Iron Hands), and its ability to provide indirect fire is great for a variety of situations. It has some reasonable durability to enemy fire, especially if they lack any form of indirect fire themselves. The Thunderfire Cannon is great for targeting a range of enemy units, but works really well for weak infantry squads, where its S5 can have most effect. It also has access to a couple of key stratagems, including the potentially game winning Tremor Shells. It is well worth the inclusion in any Space Marine army.

And remember, Frontline Gaming sells gaming products at a discount, every day in their webcart!


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