Which faction is the greatess threat to the Imperium ?

[Faultie]

In a case like this, I'd go with the multiple sources, but, as is the case with quite a few pieces of GW lore, I believe this particular question was left unanswered so as to be left up to personal interpretation and bias. Since I find the concept of Man versus His Inner Darkness to be more enthralling than Man versus Outside Threat, I prefer to believe the Gods of Chaos are more powerful. If you like Orkz more, then by all means, go with Gork and Mork. Power in the Warp does ebb and flow.

I believe this is the best answer, really, in terms of warp power. It is poorly understood by humans, and GW makes a good point to obfuscate and contradict most of their sources using other sources. I'm indifferent to Orkz vs. Marines(w/ spikes) debate. I do like to imagine the warp as a vast realm where multiple super-powerful gods can exist, and have their own regions that the others stay out of, etc.

Doesn't matter, though, because the Kroot have Dinosaurs. Boom.

[Connjurus]

I believe this is the best answer, really, in terms of warp power. It is poorly understood by humans, and GW makes a good point to obfuscate and contradict most of their sources using other sources. I'm indifferent to Orkz vs. Marines(+Spike) debate. I do like the warp as a vast realm where multiple super-powerful gods can exist, and have their own regions that the others stay out of, etc.

Doesn't matter, though, because the Kroot have Dinosaurs. Boom.

Yeah, well, uh...Chaos has flying Sting Rays!

And raptor things with crab claws and boobs and scorpion tails. WIth hooves. So not so much raptors. Uhm..

Damn it.

[Nabterayl]

Also, Chaos is most assuredly unpredictable. You can't know that your neighbor next door owes his entire success in the Grox-hide business because he gave his ninth child to Tzeentch, or that Mrs. Owens down the lane is actually a Champion of Slaanesh. Just like you don't know when, or if, or why some planet, system, or subsector is going to gain just the tiniest flicker of attention from a Chaos God for but a moment. You don't know when that Primaris Psyker is going to go critical and turn into a warp portal.

There is that aspect of it, yes, but I think that's more a question of being hard to detect or track (for a variety of reasons, not least of which is the sheer scale of the Ruinous Powers) than of being inherently unpredictable. Khorne will never surprise you by not being angry. Slaanesh will never surprise you by being selfless. Tzeentch will never surprise you by promoting despair. Nurgle will never surprise you by promoting happiness through health. You always know exactly what they want to do; what you don't know is how they're going to go about doing it.

[Connjurus]

Tzeentch will never surprise you by promoting despair. .

It won't be despair for the people that worshipped him. Most of the time. But it will cause despair in Tzeentch's foes.

Tzeentch WILL surprise you the most out of the other three because that's what he's about. Trickery, deception, subterfuge, Machiavellian plots of staggering complexity that, once they are finally unveiled for what they truly are, there's nothing that you can really do about it - especially when you find out that the only reason that Tzeentch's plan was able to come to fruition was because of some ice cream cone you bought thirteen years, four months, five days, and three minutes ago.

So yeah. Tzeentch isn't really, well, unsurprising.

[Nabterayl]

So yeah. Tzeentch isn't really, well, unsurprising.

He'll surprise you, yes. But he'll never surprise you by not being the Chaos god of hope and change. Within his vast but limited toolkit, Tzeentch can be endlessly surprising. But his toolkit is still limited. Not even the Changer of the Ways is totally mutable.

It has always seemed to me that the Ruinous Powers are not the gods of "chaos" in the sense that they are the complete opposite of all things ordered. Certain things about them are fixed - their personalities, their preferences, their portfolios, their nature as entities of the Warp rather than entities of the material plane, even their names. A "true" instantiation of chaos would not have such fixed data points. The better way to think about it, I think, is to conceive of the Ruinous Powers as the gods of "chaos" in the sense that they are the opposite of a particular order - roughly, the universe as we know it. Slaanesh would be perfectly happy to replace that order with his and her own brand of order, for instance. Even Tzeentch has certain realities that he doesn't ever seem to want to come to pass - he'll never change the ways such that he himself doesn't exist, for instance, or such that sorcery doesn't exist, or such that Nurgle defeats him, etc. Tzeentchian "order" is admittedly way more chaotic than any human mind could handle, but even it isn't totally chaotic.

[Connjurus]

I agree with you on the nature of the Gods themselves, but as they are so vast, even the ones that aren't Tzeentch...well, maybe not Khorne, but Nurgle and Slaanesh are capable of surprise. Definitely not as much as Tzeentch, but they still have it. As Gods, for Gods they undoubtedly are, their intelligences are so vast as for their motives and methods to be ineffable, unknowable. And to be unknowable is to be surprising.

As players, studying the lore from the outside, having access to all of the information that we have, most of the Gods seem rather plain. But living in the universe of 40k, and having access to even the tiniest tidbit? Pretty sure we'd be surprised by them on a regular basis.

[thelonegrif]

Orks not a chance they are too concerned with fighting (whether it be in or out) to actually try and conquer the galaxy sure one boss can unite them but that never last for very long (most of the time he gets waxed by a hero of the Impeirium or runs away and regroups)
Eldar and Tau ones race is too busy dying and trying to clean up their mess from when they ran the galaxy (dark eldar ans slaanesh) or delve into their decadence (from a Dark Eldars perspective) The Tau are too small and not growing fast enough to pose any real threat
Chaos pretty much the same story with the Eldar half the race is puritan based the other half lives for indulgence
Necorns though they may have a **** ton of undead robots running around enough las cannon shots will reduce them to nothing thier resources aren't as easily replenished
on a side note to chaos they need the Impeirium to be the way it is other wise their own in fighting will continue
(ref Daemons Codex)

im gonna have to go with nids on this one simply based on the fact that they are a united front in a sense and all they need is biomass to carry on and they are winning a war of attrition against orks come on now the hive mind is interconnected to every hive fleet (ref 5th ed nids dex) and they are an ever evolving and learning race its just a matter of time they had to leave their galaxy for some reason and im pretty sure it not because the sentient races there discovered nid repellent

[Melissia]

They aren't winning a war of attrition with Orks. We don't know who's winning.

[BuFFo]

I didn't even read the OP or the other options.

I just went in and voted Tyranids.

There is no other answer.

[thelonegrif]

They aren't winning a war of attrition with Orks. We don't know who's winning.

i retract my statement about tipping in their favor they won that war in the octarius sector against the ork refer to pages 30 and 31 of the nids 5th ed dex they killed the boss infighting took place because of the power vacuum soon that took its tool and as such the orks were divided and devoured