Barrage vs Imperial Knight Ion Shield & Vehicle Cover.

[Gleipnir]

Interesting house rule, but the justification is flawed. A ranged attack always comes from the direction of the attacker, which is how facings are determined. In the case of Barrage, cover saves and only cover saves are measured from the center of the blast marker. If the Knight is not making a cover save, and the shot originates from the facing with the Ion Shield, RAW tells us the Knight gets its Invul save. The only effect Barrage has on a vehicle is that Side AV is used instead of the facing the attack is coming from.

SJ

The center hole is not only used for determining cover saves but also is used to determine Wound allocation closest to the center of Barrage attacks which in itself implies that the source of the impact and damage radiates from the center of the blast maker, unlike standard Blast attacks which yes use the directional source of the attack.

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While we do tend to look directly down onto the Blast marker when placing it, one should also remember that (though not necessarily RAW) shots are actually fired in an arc. While even modern artillery is capable of an extreme arc in order to pass over cover/terrain that also increases the round's travel time and makes hitting a moving target very, very difficult.
Logically it makes perfect sense to me that the Ion Shield would extend upwards to at least the height of the Knight if not a little above it. Certainly protection from barrage weapons and also aircraft would have been taken into consideration by the original engineers/designers.

The fact that an Imperial Knights shields might be vulnerable to aerial or indirect fire is entirely feasible, and absent a rule that offers protections to either a top or bottom arc RAW you would ignore the shields for those attacks unless you choose to house rule it in some way.

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Certainly the wording in the rulebook could be better, or at least a simple FAQ.
But for Barrage, you consider the shot coming from the center ONLY for determining cover saves. And that vs vehicles the shots are always resolved against the side armor.

But the Ion Shield wording doesn't help as it states you get the Shied save on eh Facing that is hit. It would be more clear if it said the facing where the shot is coming from.

Bombs are different, and you would get the save depending on where the blast marker hits.

As I said earlier the source of Barrage damage is the center of the blast marker as far as wound allocation is concerned, and for vehicles its applied to the top or bottom in the case of burrowing attacks, which shares the same armor value as the side armor value.

[JMichael]

As I said earlier the source of Barrage damage is the center of the blast marker as far as wound allocation is concerned, and for vehicles its applied to the top or bottom in the case of burrowing attacks, which shares the same armor value as the side armor value.

Oh, right I forgot about that thanks.

The only facings are Front, Side (left/right), and Rear and although we see the top it is not actually a 'facing'.
So no matter what, all attacks must be Front, Side, or Rear. Just like a Flyer shooting at a Rhino where the top is the only visible (or in fire arc) part, the shot is still from the facing (Front, Side, Rear) the Flyer is in.

The Ion Shield offers a save on the Facing that is hit regardless of where the shot originates from and thus it must cover part of the top and bottom as it covers the entire facing.

If the Blast template is not placed on the exact center (which is doesn't have to be) then that certainly makes it a lot easier. To me this only really comes up if the Blast Template is centered over the center of the Knight and thus over all 4 Facings.

I guess after reading all of this, I feel the best way to resolve it is just like if the center of the blast marker is directly over 2 facings (say Side and Front). If that were the case I think we may all agree a die roll to see which armor facing the shot is resolved against.
So in the case of the center hole being directly over the center, then it is covering 4 facings and we would roll to see which of the 4 is actually hit. Then if the facing your Ion Shield is on is hit you get the save.

[SnakeChisler]

No I don't think a die roll is in order at all, the rule on barrage is pretty clear

Last example calling down bombardment Master of the Fleet Grey Knight, SM Captain whatever under your interpretation if your ion shield is facing the model that called in the bombardment you'd get a save.

The knight doesn't have an exception to barrage effects you'd need an FAQ to say it has, as pointed out with bombs its from the hole

[JMichael]

No I don't think a die roll is in order at all, the rule on barrage is pretty clear

Last example calling down bombardment Master of the Fleet Grey Knight, SM Captain whatever under your interpretation if your ion shield is facing the model that called in the bombardment you'd get a save.

The knight doesn't have an exception to barrage effects you'd need an FAQ to say it has, as pointed out with bombs its from the hole

I don't think facing of the firer has anything to do with it because of the way Ion Shield is worded. You get the Ion Shield save on hits on that facing hit. Not 'from' that facing.
So if you position the shield to your Front you only get the 4+ on any shots that HIT the front. So as I see it, if a barrage is fired the within your rear facing, but is placed or scatters onto the front facing, they you get the Ion Shield save because it is the Front facing that is hit.

[SnakeChisler]

If the central hole scatters off the model you get whatever side the blast happens to take out, as long as the hole is completely over the base of the model it counts as hitting the top (side armor value no ion save at all).

Barrage, Bombs Vector strike Fleet Ordnance etc.. just come down vertically takes side armor value on vehicles etc.. If your wanting it to work your way you really do need an FAQ

[John Bower]

I don't think facing of the firer has anything to do with it because of the way Ion Shield is worded. You get the Ion Shield save on hits on that facing hit. Not 'from' that facing.
So if you position the shield to your Front you only get the 4+ on any shots that HIT the front. So as I see it, if a barrage is fired the within your rear facing, but is placed or scatters onto the front facing, they you get the Ion Shield save because it is the Front facing that is hit.

Just read that since you mention and yes; under that wording I'm inclined to agree, No save unless the 'hit' is on that facing regardless of the firer's direction. It does make them somewhat easier to put down.

[Gleipnir]

Barrage weapons or attacks that are resolved the same as Barrage weapons where wounds are applied from the middle first, RAW do not "hit" any facing at all, they either hit or do not hit and then apply their damage to the side armor value.

Any decision to apply those attacks differently is at best a house rule, for the sake of clarification.

[JMichael]

If the central hole scatters off the model you get whatever side the blast happens to take out, as long as the hole is completely over the base of the model it counts as hitting the top (side armor value no ion save at all).

Barrage, Bombs Vector strike Fleet Ordnance etc.. just come down vertically takes side armor value on vehicles etc.. If your wanting it to work your way you really do need an FAQ

There is no 'Top' facing on any vehicle. Only Front/Rear/Side. Even though the Barrage rule states it is resolved against the side armor, it is still not the side facing.
You still actually hit the facing where the hole ends up. If the hole is directly over the left shoulder, then you hit the Left Facing and would get the Ion Shield save if it was indeed positioned to Left Side.
Also the base doesn't matter as it's a vehicle and if the blast scatters so that part of it only covers the base but not the actual model, then no hit.