This has to do with how the combat system works. The roll you're seeing is effectively the circumstantial bonuses and how well executed the power was. Each degree of success (against the opposed roll) increases the damage done by a set percent, stacking multiplicatively. Which means that the total power percentage/kills ramps exponentially in the degree of success.
And if we roll badly we can get things like all our psykers dying and summoning the 1st Circle by accident.
The psychic power rules are an obscure black box, subject to change on Durin's balancing notes.
A bad roll only has 50% of our psykers dying. The only thing that could result in all our psykers dying and the First Circle getting summoned is if we crit-fail, i.e. if we roll a nat 1. I don't think we should factor in the possibility of a nat 1 into anything we do.
Normally I'd agree, but we just burnt a shit ton of favour with the luck gods.
Assassins we have extremely strong conventional defenses against, sorcerers we don't.
'Only'
Adding on to this, how would Avernus react to Frederick demanding a warp storm to be summoned? Feels like it would go against the Third Law of Avernus; for every action, there's an equal, and opposite overreaction.
Kicking their morale roll, which Durin forgot, but then recounted and concluded it wouldn't change the outcome.
We're talking about an Exalted Greater Daemon - something that even Primarchs could lose against, such as Sanguinius when he fought Ka'Bandha the first time. None of our defences are sufficient to withstand a telepathic attack from it. We would be near guaranteed to lose heroes to death or corruption, millions or even billions of our regular citizenry would fall to Chaos or die, and worse still would be many our psykers falling to Chaos. A full blown daemonic incursion could occur from within our city walls if that happens. I consider preventing all that to be, as you would put it, "super fucking valuable".
Okay. Please explain to me how a psychic storm will prevent the Abomination from summoning the 1st Circle Angyl. As opposed to inflicting a nice amount of casualties, seeing as unless you wipe out pretty much all their sorcerers of Master+ grade, they can just keep trying again. Also, the fact that said psychic storm attempt has a nontrivial probability of making Avernus pissed at us or summoning the very daemon you're trying to prevent the summoning of.
What exactly do you think the storm is meant to accomplish? Its purpose is to take out a target that's otherwise too big or well-defended to take out conventionally, such as the Mass Conveyor where they plan to summon the First Circle.
There is a rerollable 1% chance that it could summon the daemon. That is the very definition of trivial.
1. There's no way we can get our ground troops onto the Mass Conveyor they're summoning the First Circle from in such numbers.
It's a storm, not a laser beam. It's not a targeted thing to eliminate a small selection targets, a storm by it's very nature is dispersed over a large area, making it unlikely to be sufficient to kill a heavily warded ritual site.
Ridcully only has a 50-50 chance of rerollign Natural 1s. Are you willing to bet the entire quest a single die roll?
If they summon it in space, our desperation moves can include things like 'Ram the offending ship with a Command Battleship'.
Durin said it's enough to disrupt Battle Barge kamikazes with a good roll, which I would think translates well to murdering significantly more fragile (psychically and otherwise) Mass Conveyors. But fine, it can be a beam if you want. The details don't really matter so much as the general intent of "Grand Choir kills an MC" gets through.
This is Warhammer 40,000. There is a device that can save humanity but has a 50% chance of dooming it, yet its activation is being considered because things are just that bad for humanity. We must accept that we will have to take these kinds of risks. In this case, our chance of survival in the case of a Grand Choir attack is 99+%. I think the odds of our survival if they summon the First Circle to be less than that. (Nitpick: It would be a minimum of two die rolls.)
That's more or less my opinion as well. I just want it considered as a viable option, that's all.
+ even if they throw one of their BB at us, there's still three of them left.
