Psychic phase numbers...

[ChahDresh]

TL;DR version: According to MATH, the new psychic phase results in fewer powers being cast, more selectivity over which powers you will push through, and substantially more danger for the casters. Also, Denying is hard, if non-zero.
/TL;DR

As we know, Math-hammer gives us a base of knowledge which, along with experience, informs our tactics. Since 7th hasn't been out long, and the psychic phase seems to be the big hullabaloo, some numbers about the psychic phase would appear to be in order.

I checked both the probability of getting a cast off and the odds of getting Perils of the Warp for one through seven dice. I'm sure other people have done some of this work, too, but I aimed to be comprehensive. After that will be some discussion on the implications, and the real changes between 6th and 7th.

All numbers rounded to the whole percent.

#dice	Success (1)	Success (2)	Success (3)	PERILS
1	50%	0	0	0
2	75	25	0	3
3	88	50	13	7
4	94	69	25	13
5	97	78	47	19
6	98	88	64	26
7	99	94	77	33

For reference, pass rates for psychic checks under the previous regime were:
Ld8: 72%
Ld9: 83
Ld10: 92
Perils: 6

What does this tell us?

--Fewer overall psychic powers will be getting cast relative to the old regime. Let's put this in familiar terms: say, an AM army with a brace of Primaris psykers. (Familiar to me, anyway.) At mastery level 2, casting 2 powers a turn, my expected return on psychic powers was 3.3 successes (Deny attempts notwithstanding). Under the new regime, with an assumed roll of 4 for warp charge, casting level 1 powers, I can throw two dice at each power and get off 3 with minimal Perils risk, or toss three dice at two powers and two at a third and get off 2.5 with a larger Perils risk. Throwing three dice lets me beat my Old Regime reliability, but at increased Perils risk; and however I do it, I'm getting noticeably fewer powers off. The limiting factor on casting is no longer the number of spells you know or your mastery level; it is now Warp Charge.

--You have more selectivity in which powers get cast. As part of my example above, I'm able to beat the old reliability numbers for my Ld9 psykers on two of my casts. Doing so, of course, drains me of other options. The real winners here are the Astropath and the Eldar Warlock, low-Ld psykers that previously struggled to get reliable casts. These days, by pumping additional Warp Charge into the Warlock from the other psykers in the Eldar army, you can easily up the chances of getting the low-cost Warlock powers off... if you don't mind the increased risk of frying his brains.

--Perils is substantially more dangerous, particularly if you're going for big-ticket powers. Any serious attempt to get a power off with either a) reliability or b) a Warp Charge cost of 2+ now invokes a serious prospect of pain. While there are ways to work around some of the lesser Perils effects, Mental Purge and Warp Drain are both consequential problems for psyker-spam armies.

For illustrative purposes, let's conceive of a daemon-spam list that can generate 28 Warp Charge a turn. To get the summoning powers off, all of which are Warp Charge 3, and devoting seven dice to each power, you'd expect him to get off 3 of his 4 casts and get 4/3s Perils. I think that can be dealt with.

Finally...

It's hard to Deny Blessings, but it can be done... ...just don't bother with half-measures. The odds of Perils, incidentally, are the same odds of Denying an enemy blessing that got two successes. As you can see, the numbers don't really start to get respectable until you get up to 7 dice, and even then it's only 1-in-3. Unless you're playing psyker-spam yourself, the way to go would appear to be to select the power you really, really want to Deny (say, Invisibility...), and throw all your dice at it. It also appears that Conjurations, which by necessity require three Warp Charge to go off, are going to be quite difficult to counter.

[Charon]

Actually the warlock is not a winner. While yes his chance to get a power through did increase if you take enough dice, you probably WONT generate enough dice.
To cast "Conceal" you need 1 WC, Warlock generates 1 WC.
With ld8 you had a 72% chance of succeeding.
Under the new rules you need 2 dice to get about the same level of success.
Thats 2 warlocks needed to get one power off. That means one unit you buy the warlock for goes unbuffed, thus you invested double the amount to protect just one unit.

"Winners" are low cost psykers who just fuel bigger psykers who have access to powerful schools.
While the eldar runes are good, they contain too much bad powers (Death mission is even worse than befor now) so you will end up with one or two keypowers.
I can see people skipping them for Divination.

[DarkLink]

I think to put it more precisely, the winners are psykers with access to the crazy powers who happen to have an army that can generate a lot of warp charges for cheap. Grey Knights and Daemons are the big winners there, since both can generate an absurd number of dice and Daemons get Malefic Daemonology (along with everything else) while GKs can get Divination and Telepathy.

[ElectricPaladin]

I think to put it more precisely, the winners are psykers with access to the crazy powers who happen to have an army that can generate a lot of warp charges for cheap. Grey Knights and Daemons are the big winners there, since both can generate an absurd number of dice and Daemons get Malefic Daemonology (along with everything else) while GKs can get Divination and Telepathy.

I think that armies who can field psykers who are also formidable in their own right come in a close second. The fact that Daemons can bring a couple of different kinds of monstrous creatures who are also warp charge generators is part of why they're on top. The fact that pretty much everything in a Grey Knights army generates at least a single warp charge is part of why they vie for that spot. Psychic cheerleaders are force multipliers for whichever psychic has the power you need and the speed/durability to be where you need it.

[Mr Mystery]

Maths. Not math.

Tsk.

[Blood Shadow]

I heard a great comment on the 11th Company Pod Cast where they mention how Daemons are limiting their damage output by going solely with conjurations.... If your main ranged damage dealer is witch fire powers then spamming new units won't help, in my mind this makes Daemons much worse than GK who can call on a host of ranged support without needing witchfire powers.

[ElectricPaladin]

I heard a great comment on the 11th Company Pod Cast where they mention how Daemons are limiting their damage output by going solely with conjurations.... If your main ranged damage dealer is witch fire powers then spamming new units won't help, in my mind this makes Daemons much worse than GK who can call on a host of ranged support without needing witchfire powers.

I don't think Daemons are bad, but yes, that's been my read of the situation as well. As a Blood Angels player, I would much rather see a squad of pink horrors optimized for summoning creeping up on me. That I can handle. My chances of killing them before they can do much harm aren't really all that bad. But, on the other hand, a pink horror squad with two witchfires - both of which they can theoretically use thanks to the change in how psychic shooting works - actually kind of scares me. I think that a Demon build where the pink horrors are optimized to actually do something, while the heralds and greater daemons and daemon princes, are optimized for a mix of summoning, shooting, and support, is much stronger.

[ChahDresh]

The warlock is a winner inasmuch as, if you *need* a warlock power to go off, you can gain reliability in that roll by force-feeding him dice. You are exactly correct in that you’ll often end up in a rob-Peter-to-Pay-Paul situation—that’s the complementary point to the reliability issue, that the *total* psychic output ends up dropping. That’s the main dynamic at work in the new psychic phase (and why it seems to me that it works as a game design): pick your spots.

Cheap psykers like the Astropath are part supply, but also part demand. If you have a single Primaris, for example, he’d have 2+d6 warp charge points to play with, which is enough to cast probably two powers. Add another Primaris, say, and you have enough to cast… maybe three? Because now you’re at 4+d6; a Mastery 2 psyker barely adds enough charge on his own to fuel a single power even while he knows 2-3, while an Astropath is totally dependent upon tapping the shared d6 pool to cast. And if he's not casting, he's just a battery.

Is one Warp Charge worth 25 points? That’s what an Astropath runs. Well, most AM players leap at the chance to go from Mastery 1 to Mastery 2 on a Primaris…

It’s only partially the additional Warp Charge generation that’s what you get from these cheap ancillary psykers; it’s the option to cast their powers if the situation demands it, knowing that it’s detracting from your total pool.

Really, the biggest gain that Grey Knights get is efficiency. It did individual squads little good to have Hammerhand if they never got into combat; they were psykers with untapped potential, as it were. The fact that those extra units (which are, as mentioned, useful in their own right before psychic anything comes up) contribute to the shared pool now means that, even though they might not be casting any more than before, they’re still contributing to the army’s total psychic might.

ALL of which means: psychic powers are overall less powerful than before! An AM player who buys an additional Astropath to feed his two Mastery 2 Primaris psykers is still casting three, *maybe* four powers a turn, at a lower overall chance of success with a higher overall risk of Perils. Even our Grey Knights, who are "winners", feel the burn: a level 3 psyker of theirs can only match his previous output (three powers at mastery 1 with 92% success) if he's fed nine Warp Charge more than he generates, which, by definition, can't be used by the rest of the army, with a minimal but non-zero chance to be Denied and a dramatically enhanced chance of Perils.

For all the cries of psychic apocalypse, the overall power level of psykers appears to have been toned down, but the process is now one of thought and strategery rather than a succession of mindless leadership checks. Sounds good to me.

[ElectricPaladin]

...the overall power level of psykers appears to have been toned down, but the process is now one of thought and strategery rather than a succession of mindless leadership checks. Sounds good to me.

Thank you - this is what I've been trying to say.

[Charon]

Thank you - this is what I've been trying to say.

Yes its toned down. Agree her 100%.
But I disagree on the "thought and strategy" part. If your school has just one or 2 keypowers there is no "thought" involved. You need to cast them anyways and your opponent needs to deny them anyways. No matter what you try to "feint". Thats no strategy. You could do that with stupid leadership checks as well.