I agree with coredump : in my opinion "centered" refers to the template only, it does not "double"-refer to both the template and the model (it's mostly of importance when firing on a vehicle, or on a large-base model).  For a long time I played with this double-centering, but after reading a post on this topic I realized I was reading a rule that was not written anywhere...

On the second Eldritch question : this power uses a large blast, but is not a barrage weapon.  So I think the answer is spelled out clearly on p65 : "When a vehicle is hit by a non-barrage weapon with a [blast marker ...] the shot is always assumed to hit the vehicle from the direction of the firer regardless of exactly where the marker is placed or scattered to."

Now of course, one could argue that this only applies to weapons, and that Eldritch Storm is not a weapon, but a psychic power.  From this RAW perspective, the p65 rule I quoted would not apply.  Then we would simply not know how to deal with the situation.  On the other hand, we might consider that the p52 rule about psychic powers being subject "to the usual shooting rules" ["unless specified otherwise"] makes the p65 rule applicable to psychic powers.  This whole point is debatable from a pure RAW perspective, I think.

Personally I would play it using the quoted p65 rule.

I especially liked the 'standard' mission for drop pods.

As to the last post about being half strength if the hole is not on the model, my opponet suggested that that only applied to 'weapons' and not psychic powers. Do you think it  applies to spells as well?

gb

I am not sure about the half strength rule not applying to psychic (blast) powers in general.  But for Eldritch Storm I think its specific wording points towards not halving the strength : "Vehicles affected by the blast marker take a hit with an armour penetration of [etc]".  Mind you,  I only have the French codex, so it's an "unofficial" translation back into English !

2. Conceal gives a cover save.  Flamers negate cover saves.  How much clearer could that be?  If they didn't want Flamers to negate it, they'd have made it an "invulnerable save against shooting" or something.

3.  Eldritch Storm specifically states in its description that the template is centered on the target model.  In English, when you center an object on another object that means placing the first object so that it is located as centrally as possible over the second.  So YES, you have to center it exactly on a tank if a tank is your target model. 

This is DIFFERENT from the rules for regular blast weapons, which state that the hole in the template just needs to be completely over the targeted model or the targeted model's base.  The ruling in the BGB FAQ specifies that blast markers don't need to be centered, because there is a contradiction in the rulebook between the main text on page 30, which I just paraphrased above, and the summary procedure for "Firing Blast Weapons" on the second page of the quick reference sheet in the back of the book (just before the index).  The summary instructs you to center the blast marker over the target model.  This was clearly an editing error, but it created a contradiction, hence the need for the ruling in the FAQ.

Eldritch Storm is a psychic power.  The rules for psychic powers (p 52, BGB) state that unless otherwise specified, they follow the rules for shooting.  Eldritch Storm specifies in its description that it is an attack using the Large Blast rules, so those will control unless explicitly contradicted by the power's description.

Eldritch Storm specifies that the template IS centered on the targeted model, hence it does not follow the usual rules for placement of blast templates.  It must be centered on the targeted model.

Eldritch Storm goes on to say that vehicles touched by the template suffer a hit with 2d6 +3 armor penetration.  That instruction does seem to me to contradict and override the usual rules for blast weapons hitting vehicles, which require that the Strength of the weapon be halved before rolling to penetrate if the hole in the template is not on the vehicle you are rolling against.

Eldritch Storm does not say anything about what direction the shot is considered to be coming from, so we revert to the rules for blast weapons in general (p30, and p65).  As noted, page 65 tells us that for a blast or Large Blast weapon, the AV rolled against depends entirely on which facing the firer is in. 

IF Eldritch Storm were a Barrage weapon, then the shot might potentially be considered to come from some other direction in certain circumstances (see p 31), but since Eldritch Storm does not have the word Barrage anywhere in its rules, the rules for Barrage weapons do not apply.

• The centre of the Blast marker ends over the
vehicle’s hull.
In this case the shell/missile has hit the vehicle and
exploded on it. The armour penetration roll is
resolved against the armour value facing the firer,
regardless of the position of the marker, using the
full Strength of the weapon.
• The centre of the Blast marker ends outside the
vehicle, but part of the marker covers the vehicle’s
hull.
In this case the shell/missile has missed the vehicle,
and only some shrapnel clanks against the vehicle’s
armour. The armour penetration roll is resolved
against the armour value facing the centre of the
marker, regardless of the position of the firer,
using only half the Strength of the weapon
(rounding down).