In some 40k literature the Imperium and the Inquisition in particular use ratings to quantify psychic power. They use the Greek letter system and if I recall include Gamma, Beta, Alpha, Alpha-plus (apocalyptically powerful), with the lower greek letters being less powerful.

My question is, how do you suppose these ratings exist with the meta psy ratings in the rulebook?

I personally wouldn't put anyone in the rulebook above a Gamma rating ... Gamma+ maybe. Characters, even by the time they graduate the core book, are not on the level of people like Eisenhorn, or Ravenor. Which isn't to declair them weak, far from it! But merely not on par wiht powerful psykers or prefessional Inquisitors. I'd wait for the next player buffing excessory to come out before seeing that.

They use the Greek letter system and if I recall include Gamma, Beta, Alpha, Alpha-plus (apocalyptically powerful), with the lower greek letters being less powerful.

They actually "wrap around" at Alpha, meaning you have Beta, Alpha, Alpha+, Beta+, Gamma+, etc, all the way up to Omega+, which would be a Chaos Deity. I'm not quite sure but I think Omega was a blank/pariah.

I don't think you can map psy ratings to the letters since the imperial rating is supposed to be static. You either are a beta psyker or you're not - you don't train to become one. Only things like daemonic pacts would change your rating. The rating marks potential in total, not present power.

We know about the ratings that Gamma is pretty powerful for a human (Ravenor) while Zeta is often already considered not worth salvaging and training (Zusen from Scourge the Heretic, though she was tainted too). Alpha and Alpha+ are considered too powerful to train since they might enslave a planet on a whim should they snap. I'd guess most player psykers would fall into Delta grade.

Cifer said:

As I understand it, the greek letter, or 'Abnett' scale covers baseline psychic potential - your raw talent, with no other consideration. It doesn't inherently match up to the trained Psy Ratings present in DH. Personally, I felt the extrapolation of the system in The Inquisition to be a rather clunky approach, especially the 'mirrored scale' (Alpha-Plus to Omega-Plus) tacked onto the top of the system... it always felt more appropriate to me that "Alpha-Plus" meant "above the scale, power that we cannot categorise" rather than simply being another grade.

Back to the matter at hand: Psy Rating doesn't directly correlate to the Abnett scale of psionic potential measurement. That was not always the case. Back during the early playtest, the Psy Ratings were named, covering the top six grades of psychic ability (Psy Rating 6 being Alpha), with a psyker's Psy Rating being determined at character generation and remaining largely static (a character could naturally and with exceptional effort increase his rating by one... and could, through vile and debased methods, corrupt himself to increase it further). The powers scaled quite a few elements by Psy Rating instead of the relevant psychic stat (which was also different back then, mainly because the profile was very different) as well, meaning that a character with a higher Psy Rating was able to create naturally bigger and more significant effects than weaker psykers.

I generally agree with what's been said above. While I don't think there's an exact correlation between the greek letter-based system and game mechanics, I think PC psykers should be somewhere in the delta/epsilon levels.

Alpha-plus through Gamma are so powerful they would be likely to unbalance/break your game. Anything lower than Epsilon may not be powerful enough to be of service to an Inquisitor as an acolyte, and most of these that aren't killed outright are probably consumed to sustain the Emperor or serve in the Adeptus Astronomica.

I also agree that the ratings measure potential power, and are extremely unlikely to change with experience/training.

There's a nice rundown of this on Dark Reign, which includes TS Luikart's take (he's the designer of the Psyker stuff in DH and is probably reading this as I type it via the Warp).

Here's the quote for the best rating you can accomplish via ingame powers:

"To be rated as a Gamma Grade Psyker you must possess at least the Dark Heresy Psy Rating Talent grade 5 and have both the Talents Power Well and Discipline Focus. You must also be either the Master of a single Psychic Discipline, e.g. 10 powers (or more) or you must have 7 Discipline Powers from two or more Disciplines. If you have the bulk of the requirements, only lacking say 1 power, you are likely rated as a low level Gamma. If you have a Psy Rating 6 with the above, you are likely regarded as a Gamma+ or a low level Beta."

(http://www.darkreign40k.com/psychic-powers/psyker-grades-game-mechanics.html)

Presumably you can bump your way up to Beta with Psychic Supremacy, although you'd still be on the low end of the spectrum in terms of raw power.

I seem to remember reading somewhere that some Inquisitor Lords manage to push themselves up to a stable Alpha, so maybe we'll see that in Ascension.

Hodgepodge said:

I'd be interested to read something in the canon that says anyone in the Inquisition was an Alpha level psyker. Setting aside as incorrect Orfeo Culzean's statement in Ravenor Rogue that Gideon Ravenor was an Alpha-plus psyker, Ravenor is elsewhere described as a Delta-grade psyker. IIRC Beta is the highest level a human being can attain and still be considered sane, but even then you are talking about a being of immense power far greater than even the great psyker Inquisitors we know from the fiction, like Eisenhorn, Ravenor, Commodus Voke, Heldane, etc. This person would be able to completely control the minds of multiple people at once or crush a man to death against a wall in a matter of seconds without even breaking a sweat. The only good write-up I've read about an Alpha-level human was in Malleus during the aftermath of the atrocity on Thracian Primaris. Esarhaddon is described as Alpha-level, and he has the ability to turn hundreds of people into puppets simultaneously, forcing them to fight to the death with no concern for their own safety in order to protect himself from the Inquisition.

I've read that write-up on Dark Reign, but I must say I think that sounds a little overpowered for the RPG and not consistent with the game fluff. I understand the author's purpose is to allow for character development and progression in the RPG, but I always conceived of the grades as measures of potential, not actual present power level.

But, full disclosure, we use house rules in my game, and don't cleave to the core rules on psykers at all. That's a different discussion for a different topic, but suffice it to say IMHO psykers shouldn't be OP in the game and ordinary uses of telepathy/telekinesis shouldn't expose the PC to any appreciable risk of possession, etc. When Patience Kys pins a dude to a wall with her kine blades, she is not exposing herself to any serious risk of possession or another so-called "peril of the warp." There's always *a* risk, but it's extremely small. I mention Patience because I think she's an excellent template for a PC in DH.

Well, it would help if I recalled where I read that a small amount of Inquisitor Lords (as well as Space Marine Librarians) had managed to attain Alpha status. By "small amount," if I recall correctly, the source meant "in the last 10,000 years," rather than "at the present moment in Imperial history."

Just out of curiosity, what Psy rating was the Emperor? He's a special case, but wouldn't be be above Alpha+? I'm not familiar enough with the material to say. I do recall a summary of the Horus Heresy mentioning him engaged with all 4 Chaos Gods psychically as he fought Horus, but I have no idea if that is remotely accurate.

The God-Emperor maintains the entirety of the Astronomicon.

It's not hyperbole to say that he's beyond petty ranking systems applied to mere mortals.

DarkPrimus said:

I agree that the Emperor is "off the charts" in terms of his psychic power. If certain factions are correct, he would dwarf all 4 Chaos Dieties...if he were allowed to die and his soul fully enter the Warp...but that's a different discussion for a different topic.

And, not to quibble, but the Emperor's will merely directs the psychic light of the Astronomican. He does not power it himself. It is actually powered by the 10,000 Psykers comprising the Chosen of the Adeptus Astronomica, who have to be replaced by the hundreds every month because their task completely consumes them.