Just how does the Psychic Scourge device work? Ok, we know the device was used by Possessed Drogan to summon Nemeroth. But before his possession Drogan seemed on the edge of completing it (as evidenced in the audio skulls). He states in one log that the warp energy 'attacks the psychic parts of the creatures brain'; and leaves the Humans unscathed. But how would it affect the Orks? They have a seperate collective psychic field outside the warp(the WAAAGH!), so they can't be corrupted by Chaos or mutated by it. I can only imagine the device works by tapping into the Waaagh and filling it with warp energy (which would logically work at doing something terrible to the Orks as warp energy would be anathema within the Ork psychic field). It isn't helped that Drogan mentions in another log of doing experiments on the tau, who little to no warp presence. If anyone could fill holes in my knowledge, cheers.
Just about all creatures have some psychic parts of their brains. The Psychic Scourge works by targeting and destroying said parts of their brains. Orks' psychic abilities still come from the Warp (Weirdboyz still have to roll Perils of the Warp, for example) but they're much more resistant to corruption. That doesn't mean a psychic attack won't explode their brains (which happens to Weirdboyz often enough). Ditto for the tau; they still have a warp presence, but it is very limited. The Scourge, from what I gathered, could be keyed to target anything that wasn't human (and could still kill humans, in case someone needed to do a clean Exterminatus). Of course, the Scourge could also be used to open a Warp Gateway, or at least the Power Source could be used as such. Who knows, maybe Drogan was completely out of his gourd and was being prodded in that direction by Chaos the whole time. It's happened to Inquisitors before.
Those weapon-shrines. Why keep weapons locked up in there, on the off chance that a Space Marine might come by and need it, especially since you can see the same weapons lying around (in Guard encampments no less, who can't even use them...)
Those were dropped in from orbit for Marines to use.
About weapon-shrines: I guess it's the same as the titan, the whole planet makes weapons, which are meant to be used off-world. I think the shrines will give the weapons not only to space marines, but also the inquisition, battle sisters, etc. The shrines will probabaly even give the weapons to higher-ranked elite guardsmen.
How IS Titus immune to the Warp's energies?
The Emperor did it. It's the warp, logic is ancillary.
Alternatively: Titus is a Khornate servant.
Alternatively alternatively: He could be an Untouchable (if a Space Marine can even be one that is, don't think the fluff has said one way or another)
In a non-guessing answer, the game offers no answer. Maybe a sequeal will tell us, maybe not.
What are those dots on Titus's forehead? He looks like he's got a couple of nails driven into his skull.
Service studs. Usually represent a century of service.
Nemeroth is a Chaos Sorcerer, why is he able to command Bloodletters?
You know, the whole 'Khorne never uses Sorcerers' thing is really stupid. How do you summon Bloodletters otherwise? Wave a sharp stick around until they just pop out of the air? Besides, Nemeroth seems to follow Chaos Undivided, and they tend to be more fluid about those things.
Khorne hates magic, but it's not like he never uses it (magic wargear, etc.)
To add on: Khorne hates magic not because of magic itself, but because a large part of what magic does doesn't jive with his theme. As a Chaos manifestation of martial bloodletting, he would obviously see the advantages of magical teleporation/speed towards the enemy, daemon swords, and even possessed bolters and cannons, but he'll roar his discontent at a sorceror firing off a bolt of chaos literally out of nowhere instead of getting his hands dirty.
I was always under the impression that the orks acting smart (using big guns instead of looting them, etc) was because they were being manipulated by Chaos. Is that the case, or are they actually smart (see Genius Bruiser for the warboss)?
Probably a mix of both, although your average ork is smart enough to know to use giant guns rather than loot them (unless they have a mekboy with them. Orks would never waste perfectly good Dakka unless they thought they could make even more Dakka out of what they wasted (and given the way ork science works if they think they can they usually can).