Whirlwind vs Thunderfire cannon

[Arkios]

Just quickly on this, if you bolster the ruin that the TM & TC are in do both benefit from the +1 to the cover save and, on that line of thinking, any vehicle (say a Dreadnought for example) deployed within the ruin)?

I mean if the artillery piece or vehicle receives a cover save from the ruin wouldn't that mean it would also get the bonus from the Bolster defences rule?

 

Well, the rules for 'Bolster Defenses' states that a piece of ruins (and only ruins) can be bolstered to increase the cover save it provides by 1. The rules for vehicles in cover state that if the vehicle is at least 50% obscured, it may take a cover save "exactly like a non-vehicle model would do against a wound (for example, a save of 5+ for a hedge, 4+ for a building, 3+ for a fortification, and so on)".

 

So yes, a Dreadnought (or any other vehicle for that matter) can get a 3+ cover save if they are obscured at least 50% by a bolstered ruin.

 

 

Now as to the Thunderfire Cannon getting a cover save...

At my FLGS we use the INAT FAQ (found here), which states (on page 12) that artillery units are treated just like infantry units when determining whether the unit as a whole gets cover saves (ie- half the models or more have to be considered in cover to give the entire unit cover saves), BUT the gun model is treated as a vehicle (must be 50% obscured) in order to determine whether it contributes as one of the models in the unit being in cover.

 

So according to this ruling, the Thunderfire Cannon can be out in the open while the Techmarine Gunner is behind cover or in area terrain, and both will get their cover save. Likewise, the Gunner can be out in the open and the Cannon can be 50% obscured (vehicle cover rules) and, again, both models will get their cover saves due to half the models in the unit counting as being in cover.

 

Obviously the first scenario is much easier to accomplish, so I'd just stick with doing it that way. Just remember that, in order to fire the Cannon at a target, you need to be able to draw LOS to the target from BOTH the cannon AND the gunner.