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 Ashiraya wrote:

 dusara217 wrote:

Ashiraya wrote:The Imperium is like GW. They are big because they were big yesterday, not because they are good at what they do.

The Imperium is just a lot bigger than GW and pretty much took the galaxy for itself at the end of the Great Crusade, meaning it has taken a very long time for it to be as properly challenged as it is in 40k.

You do realize that most of the IoM's territory was conquered during the Forging (a two-thousand year period), not the Great Crusade, right? It's downright moronic to even contemplate believing that the entire galaxy could be conquered in 200 years, and even 2,000 years is pretty far-fetched.

It's also pretty damn moronic to imagine a dude pushing up a Titan's foot from underneath it, but the Great Crusade was a weird time. That is not a reason to be snide.

I also could not find a source stating that the Forging was more important than the Great Crusade in this.

Forging was quite important it was before the great crusade if I remember correctly and even before the dark age of technology.

No, it was after the Great Crusade.

 Vaktathi wrote:

haiharoshin wrote:

 KamikazeCanuck wrote:
There are individual planets in the IoM that aren't even famous that could destroy the ME Universe by themselves.

as mentioned before, the warp doesn't apply to the ME universe, This means that it would make it rather difficult for the races of 40k to get anywhere, let alone individual planets. and Depending on the type of world your referring to, would it be able to sustain a total war against a universe with greater mobility while in its own universe, as well as control of many planets. Even the IoM planet has greater firepower (which I'm sure it does.) it would still need supply lines to sustain the war effort. and I doubt a single IoM world can devote the supplies for a war on a galactic scale. The ME races could simply attack weak targets, and attempt to destroy any available supplies for the Imperial navy to use.
Not to mention that the IoM wouldn't have the Mass Effect technology. Making it impossible to get from planet to planet.
At best it would end in a stalemate. With the IoM planets taking a foothold but unable to make any further progress, while having to defend constant attacks from ME forces.

If you're not applying the Warp to the calculation, then the Mass Effect can't apply either. Really, these are fantasy crutches that both universes rely upon to underpin the functionality of their realms, and without them, neither universe works.

Exactly. It's a very bad premise for a fight. It's like saying imagine a boxing match where no one leaves their corner!

 KamikazeCanuck wrote:

 Vaktathi wrote:

haiharoshin wrote:

 KamikazeCanuck wrote:
There are individual planets in the IoM that aren't even famous that could destroy the ME Universe by themselves.

as mentioned before, the warp doesn't apply to the ME universe, This means that it would make it rather difficult for the races of 40k to get anywhere, let alone individual planets. and Depending on the type of world your referring to, would it be able to sustain a total war against a universe with greater mobility while in its own universe, as well as control of many planets. Even the IoM planet has greater firepower (which I'm sure it does.) it would still need supply lines to sustain the war effort. and I doubt a single IoM world can devote the supplies for a war on a galactic scale. The ME races could simply attack weak targets, and attempt to destroy any available supplies for the Imperial navy to use.
Not to mention that the IoM wouldn't have the Mass Effect technology. Making it impossible to get from planet to planet.
At best it would end in a stalemate. With the IoM planets taking a foothold but unable to make any further progress, while having to defend constant attacks from ME forces.

If you're not applying the Warp to the calculation, then the Mass Effect can't apply either. Really, these are fantasy crutches that both universes rely upon to underpin the functionality of their realms, and without them, neither universe works.

Exactly. It's a very bad premise for a fight. It's like saying imagine a boxing match where no one leaves their corner!

Well that is until one of the boxers finds out they can take their glove off and throw it at the guy in the other corner.
Both are able to travel well within a solar system. but need a more effective means of transportation to go longer distances (the warp for 40k, and Mass Relays for ME.) The question is which faction can adapt the fastest to accommodate for the disadvantage they have in enemy territory. basically, who has the best science divisions?

 Ashiraya wrote:
Of course, once you take the fleets into account... Hmm, it struck me that the ME games never really showed us any Krogan ships, did they?

They existed. Krogans weren't legally allowed to have ships after the Krogan Rebellions, but they DID have them before. Krogan technology was notably robust and reliable, and Tuchanka had anti-ship batteries capable of destroying naval combat vessels in a single shot. Part of the importance of the Krogans being led by Wrex and Eve as opposed to some random warlord with a chip on his shoulder was that they were working on recovering the lost glory of the Krogan civilization of old.

Indeed, even though it was pre-spacefaring, a Krogan power grid schematic was considered actually superior to what the super-advanced spacefaring races used on the Citadel. And Krogan engineers can be seen in the ending of ME3 working on what appears to be plans for a ship of their own. Because the ME3 universe is in constant flux and is explicitly a story about progress, you have to ask "what part of the timeline are we talking about" when doing vs matches.

Yes the Krogans are stereotyped as stupid ork like beings, but they had a thriving civilization once and will again. Saying you got out strategized by the Turians is like saying your having some issues defeating Rommel or Hannibal Barca these are some of the best strategists around.

They still had tons of restrictions on them until they were cured.

Krogan are smart. About as smart as humans at any rate. It's just too easy for a large bulk of their population to descend into less than civilized people due to the fact that they went from tribal war bands to space faring people in the span of a few decades with none of the social development that comes with progress. The average Krogan can live for 400 years. By the time of ME 3 there has only been a few Krogan generations since they were uplifted into space.

 Ashiraya wrote:

 dusara217 wrote:

Ashiraya wrote:The Imperium is like GW. They are big because they were big yesterday, not because they are good at what they do.

The Imperium is just a lot bigger than GW and pretty much took the galaxy for itself at the end of the Great Crusade, meaning it has taken a very long time for it to be as properly challenged as it is in 40k.

You do realize that most of the IoM's territory was conquered during the Forging (a two-thousand year period), not the Great Crusade, right? It's downright moronic to even contemplate believing that the entire galaxy could be conquered in 200 years, and even 2,000 years is pretty far-fetched.

It's also pretty damn moronic to imagine a dude pushing up a Titan's foot from underneath it, but the Great Crusade was a weird time. That is not a reason to be snide.

I also could not find a source stating that the Forging was more important than the Great Crusade in this.

http://wh40k.lexicanum.com/wiki/The_Forging
http://warhammer40k.wikia.com/wiki/Age_of_the_Imperium#The_Forging_.28c._M32_-_c._M35.29
Also, 5th Edition Rulebook


Automatically Appended Next Post:
Also, there are at least 100 billion planets in the galaxy, I find the idea of the Imperium's "dominance" over it preposterous, in and of itself, but that's beside the point.

EDIT: Also, any war that the Imperium of Man embarks upon (in the Great Crusade), that I've read about, took at least a year. Assuming that there are 20 Crusade Fleets for every Legion, that means 360 conquered planets. Double that, and we're at 720 planets. Triple it, and we're 1,080. Assuming that we've got about a Demi-Chapter's worth of Marines in each Crusade Fleet (and enough Crusade Fleets to match), then we've got 1,080 per year. In 200 years, we've got 216,000 planets.

Also, sorry about sounding pissy.

From the Mass Effect wiki it is stated that a Reaper Sovereign class battle ship (their largest kind) is armed with a cannon that has a yield of 132-450 kt TNT and its stated that this power dwarf the main gun of an evers-class alliance dreadnaught and that no known ship has been known to survive a hit.

To put this in perspective the bomb that fell on Hiroshima had a yield of 15 kt TNT.
A W88 warhead has a yield of 475 kt TNT = we today have a stronger (thought only one "use") weapon than that of the reapers.

But with that said a Tsar-Bomb has a yield of 50,000 kt TNT so yeah...

 salix_fatuus wrote:
From the Mass Effect wiki it is stated that a Reaper Sovereign class battle ship (their largest kind) is armed with a cannon that has a yield of 132-450 kt TNT and its stated that this power dwarf the main gun of an evers-class alliance dreadnaught and that no known ship has been known to survive a hit.

To put this in perspective the bomb that fell on Hiroshima had a yield of 15 kt TNT.
A W88 warhead has a yield of 475 kt TNT = we today have a stronger (thought only one "use") weapon than that of the reapers.

But with that said a Tsar-Bomb has a yield of 50,000 kt TNT so yeah...

Well a nova cannon barrage would disintegrate the entirety of a reaper. leaving little but ash behind.

Or you know a bunch of battle barges just ramming into the sovereign class breaking into it and breaking it into pieces.

Fanfiction.net has this topic covered many times over.

 Asherian Command wrote:

 salix_fatuus wrote:
From the Mass Effect wiki it is stated that a Reaper Sovereign class battle ship (their largest kind) is armed with a cannon that has a yield of 132-450 kt TNT and its stated that this power dwarf the main gun of an evers-class alliance dreadnaught and that no known ship has been known to survive a hit.

To put this in perspective the bomb that fell on Hiroshima had a yield of 15 kt TNT.
A W88 warhead has a yield of 475 kt TNT = we today have a stronger (thought only one "use") weapon than that of the reapers.

But with that said a Tsar-Bomb has a yield of 50,000 kt TNT so yeah...

Well a nova cannon barrage would disintegrate the entirety of a reaper. leaving little but ash behind.

Or you know a bunch of battle barges just ramming into the sovereign class breaking into it and breaking it into pieces.

Yeep, also add that Reaper shields (if my memory serves correct) can't negate hits from 40k Lances.

Shepard probably brokers an alliance with the Tau, gets it on with Tau girl and with some Eldar help dig in and blunt the IoM's attacks. Another thing ME has going for it, is very advanced shielding and cyber warfare that is miles beyond anything in 40K. It's even likely the Reapers could take over the Necrons just like they did the Geth. The Imperium's computer networks are basically brain dead servitors and systems that can barely process like a TI-82. They'd be severally vulnerable in the department.

Where the 40K universe has what would if completely played out the winning edge, it'd be numbers and volume of fire. Lasguns and even bolters are garbage compared to the assault rifles in ME alone but when it's 10,000-100,000 to one, quality doesn't mean much.

 Asherian Command wrote:

 salix_fatuus wrote:
From the Mass Effect wiki it is stated that a Reaper Sovereign class battle ship (their largest kind) is armed with a cannon that has a yield of 132-450 kt TNT and its stated that this power dwarf the main gun of an evers-class alliance dreadnaught and that no known ship has been known to survive a hit.

To put this in perspective the bomb that fell on Hiroshima had a yield of 15 kt TNT.
A W88 warhead has a yield of 475 kt TNT = we today have a stronger (thought only one "use") weapon than that of the reapers.

But with that said a Tsar-Bomb has a yield of 50,000 kt TNT so yeah...

Well a nova cannon barrage would disintegrate the entirety of a reaper. leaving little but ash behind.

Or you know a bunch of battle barges just ramming into the sovereign class breaking into it and breaking it into pieces.

Physical contact is ill advised. The closer you are the faster indoctrination will take hold. Stick with the long ranged bombardments.

 Gamgee wrote:

 Asherian Command wrote:

 salix_fatuus wrote:
From the Mass Effect wiki it is stated that a Reaper Sovereign class battle ship (their largest kind) is armed with a cannon that has a yield of 132-450 kt TNT and its stated that this power dwarf the main gun of an evers-class alliance dreadnaught and that no known ship has been known to survive a hit.

To put this in perspective the bomb that fell on Hiroshima had a yield of 15 kt TNT.
A W88 warhead has a yield of 475 kt TNT = we today have a stronger (thought only one "use") weapon than that of the reapers.

But with that said a Tsar-Bomb has a yield of 50,000 kt TNT so yeah...

Well a nova cannon barrage would disintegrate the entirety of a reaper. leaving little but ash behind.

Or you know a bunch of battle barges just ramming into the sovereign class breaking into it and breaking it into pieces.

Physical contact is ill advised. The closer you are the faster indoctrination will take hold. Stick with the long ranged bombardments.

Indoctrination is a slow process, and its sound based.
Sound cannot travel in space so it has no effect on ships.
Noice Marines have tried similar things before and with how Chaos work the indoctrination is nothing the Imperium havent seen before.
Space Marine helment most likely just filter out the sound rendering it useless.

That's not actually completely correct. It's assumed to be sound based, but has an electromagnetic component. Most humans can be controlled within hours if need be or at least influenced. And unlike the warp and the noise marines this is a scientific effect and we all know how dumb the Imperium is. I would advice against ramming when even the weakest of ranged weapons is more than enough. All it takes is one hidden reaper drone to stick to the outside of a ship. Why give them that chance?

 dusara217 wrote:

http://wh40k.lexicanum.com/wiki/The_Forging
http://warhammer40k.wikia.com/wiki/Age_of_the_Imperium#The_Forging_.28c._M32_-_c._M35.29
Also, 5th Edition Rulebook

The former link doesn't state just how much of an impact the Forging had vs the Great Crusade.

I shall ignore the latter because the 40k wiki lacks inline citations, making it infamously unreliable.

If the rulebook says it, it's another matter, but you will need to quote the passage and ensure it has not been retconned in later editions.

 dusara217 wrote:
Also, there are at least 100 billion planets in the galaxy, I find the idea of the Imperium's "dominance" over it preposterous, in and of itself, but that's beside the point.

It is worth remembering that almost all of those 100 billion planets are lifeless rocks, largely irrelevant except possibly for mining (and very rarely for terraforming).

Also, any war that the Imperium of Man embarks upon (in the Great Crusade), that I've read about, took at least a year.

It's worth considering that any battle we get to read about is going to be close-fought, because nobody enjoys reading 'Imperium shows up, secures compliance shortly with their display of power, compliance goes smoothly and the Crusade goes on.' That doesn't necessarily have to mean that the stories we get to read about are representative of the majority.

 Gamgee wrote:
That's not actually completely correct. It's assumed to be sound based, but has an electromagnetic component. Most humans can be controlled within hours if need be or at least influenced. And unlike the warp and the noise marines this is a scientific effect and we all know how dumb the Imperium is. I would advice against ramming when even the weakest of ranged weapons is more than enough. All it takes is one hidden reaper drone to stick to the outside of a ship. Why give them that chance?

do you really think that any fleet based action would be in EMCON? Or that AI based life wouldn't have superior ECM, ECCM, or another way to hack Fleet Comm? While it is true that sound doesn't travel in space, other forms of communication get through just fine.

To compare fleets in a effective way, we should compare their capabilities at different ranges, Armour capabilities, maneuverability, as well as each factions strategies for space combat.
Also, I recommend we keep the scales of each fleet relatively similar. This way, a battle isn't dictated by the massive battleships 40k possesses.

 carldooley wrote:

 Gamgee wrote:
That's not actually completely correct. It's assumed to be sound based, but has an electromagnetic component. Most humans can be controlled within hours if need be or at least influenced. And unlike the warp and the noise marines this is a scientific effect and we all know how dumb the Imperium is. I would advice against ramming when even the weakest of ranged weapons is more than enough. All it takes is one hidden reaper drone to stick to the outside of a ship. Why give them that chance?

do you really think that any fleet based action would be in EMCON? Or that AI based life wouldn't have superior ECM, ECCM, or another way to hack Fleet Comm? While it is true that sound doesn't travel in space, other forms of communication get through just fine.

I wasn't talking to you, but I agree with you. I was talking to the poster above me who said ramming them would be a good idea.

 Gamgee wrote:

 carldooley wrote:

 Gamgee wrote:
That's not actually completely correct. It's assumed to be sound based, but has an electromagnetic component. Most humans can be controlled within hours if need be or at least influenced. And unlike the warp and the noise marines this is a scientific effect and we all know how dumb the Imperium is. I would advice against ramming when even the weakest of ranged weapons is more than enough. All it takes is one hidden reaper drone to stick to the outside of a ship. Why give them that chance?

do you really think that any fleet based action would be in EMCON? Or that AI based life wouldn't have superior ECM, ECCM, or another way to hack Fleet Comm? While it is true that sound doesn't travel in space, other forms of communication get through just fine.

I wasn't talking to you, but I agree with you. I was talking to the poster above me who said ramming them would be a good idea.

no worries.
I imagine that ramming a Reaper vessel would not be terribly effective. For the same reason why Ion Accelerators for Riptides, and Missile Pods for Crisis Suits, (and Pulse Driver Cannons for Stormsurges - if I ever get one) will almost always be my preferred weapon system. Range. As you get closer, the more weapon systems can engage you, and the more effective their targeting would be.

 KingmanHighborn wrote:
Shepard probably brokers an alliance with the Tau, gets it on with Tau girl and with some Eldar help dig in and blunt the IoM's attacks. Another thing ME has going for it, is very advanced shielding and cyber warfare that is miles beyond anything in 40K. It's even likely the Reapers could take over the Necrons just like they did the Geth. The Imperium's computer networks are basically brain dead servitors and systems that can barely process like a TI-82. They'd be severally vulnerable in the department.

Where the 40K universe has what would if completely played out the winning edge, it'd be numbers and volume of fire. Lasguns and even bolters are garbage compared to the assault rifles in ME alone but when it's 10,000-100,000 to one, quality doesn't mean much.

Except that you're looking at having to use Indoctrination, not hacking, to take over the Imperium's biological-based computers.

As for shielding, Mass Effect kinetic shields are utterly pathetic compared to Void Shields on a starship scale, and infantry-scale Kinetic Barriers are going to do jack all against a lasgun, while the average Mass Effect personal firearm is basically a shuriken catapult.

Never said ramming would be a good idea only that Indoctrination would not be that effective against the imperium.

You are right about indoctrinations exact mechanics is unknown but is belived to be an eloctromagnetic field and/or infra sound and ultrasound (maybe both).

Thou full control would take more time then the reapers would have if they ever ended up fighting the imperium. Just look at the victory fleet in ME3 none of them got indoctrinated.
And corruption from the "inside" is nothing the imperium isn't used to so indoctrination would not have the same effect as it has in ME universe.
That and the Imperium would have no issue blowing up an entire planet if they where deemed indoctrinated.

They didn't get corrupted because they were kept isolated as a people for the final push on the citadel and kept around the dev ices super hidden building location. Most of them didn't fight the Reapers at all after the initial engagements as the most trustworthy loyal and people who would unlikely to be exposed to indoctrination were put to guarding this secret location that no Reapers got to.

You simply can't say that since there is no evidence in your favor that none of our ships turned mid fight.

Not really what I was referring to but definitely an interesting piece of trivia. Never finished ME3 so don't know much up until the victory fleet, since well epic space battle.

Lets put it this way then, is there any case of someone turning mid combat?
As all evidence I can find is that indoctrination (full control that is not the other effects such as paranoia) take days or longer depending on the victims will power.

Javik the Prothean says he seen ships turn in combat against them and it was surprising because of how fast it was. It's ambiguous how fast they turned though. I'm a complete Mass Effect nerd man. Beat the first game like 28 times, the second 12 and the third 3 times. Read all the books barring one and the majority of the comics. I know my lore. Way better than I do 40k.

 Gamgee wrote:
Javik the Prothean says he seen ships turn in combat against them and it was surprising because of how fast it was. It's ambiguous how fast they turned though. I'm a complete Mass Effect nerd man. Beat the first game like 28 times, the second 12 and the third 3 times. Read all the books barring one and the majority of the comics. I know my lore. Way better than I do 40k.

40k is used to temptation.

The necrons would make short work of the reapers.

PLease notice there is a reason why no one can hack the necrons as they are not AI, they are biological beings that became robots. So they are sentient. (Well a few of them are.) Most warriors aren't but their leaders and nobles retained much of their previous sentience if not more....

eceived new bodies of similar quality. Soldiers received bodies that were merely adequate. The everyday citizens of Necrontyr society received the leftovers; comparatively primitive bodies that almost served as prisons: these, now the Necron Warriors, are incapable of feeling almost all emotion, and retain little sentience.[1a] It was a given that the civilian necrontyr would not receive the same care as their betters during biotransferrence, but it is possible that this mental degradation was intentional: all the better for the nobles to command their servants and receive total, unconditional loyalty.[1b]

http://wh40k.lexicanum.com/wiki/Necron_Warrior

Astartes in general could resist alot of tempation, plus the mass effect universe is not used to fights and battles over kilometres of distance. Infact 40k space battles are over extremely long distances. Infact by the time the Alliance navy would get to an Imperial Navy Carrier they would be blasted apart by imperial navy cruisers or fighters.

The Reapers would be torn apart by sheer distance and firepower of an imperial naval battlement group. (Which usually consists of seven really big ships, a carrier, and its flotilla and escorts to help with smaller targets). (They also have fighters at the ready at least 32 per captial ship, and bombers to deal with destroyers and such)

The Imperial Navy would keep its distance due to they would probably be far more effective at a distance. A single crusade would make much of the mass effect universe burn and fall apart, and would cause much of its military to simply fall apart. A military group and weaponry that far exceeds their own.

It's not about simple temptation. It's a literal override of your mental faculties. A biological effect that no biological species seems able to resist. They use straight up hacking to take control of machines though since indoctrination won't work on them.

Ordinary humans in 40k would fall in droves to its powers if Reapers got close enough. Space Marines might be able to resist it better, but eventually would succumb.

However 40k ranged weapons are all so powerful there should be no reason to get close enough to them. If the 40k universe is stupid and marches into melee against Reapers they could swiftly face routes on planet after planet and entire fleets turn against them.

All it takes is one person to start it all. Which is why I'm arguing why even bother with melee when your ranged weapons are overkill and would annihilate the Reapers.

This is all theoretical and damned be any fool who gets too close to them or heavens forbid space marines try board them.

 Gamgee wrote:
It's not about simple temptation. It's a literal override of your mental faculties. A biological effect that no biological species seems able to resist. They use straight up hacking to take control of machines though since indoctrination won't work on them.

Ordinary humans in 40k would fall in droves to its powers if Reapers got close enough. Space Marines might be able to resist it better, but eventually would succumb.

However 40k ranged weapons are all so powerful there should be no reason to get close enough to them. If the 40k universe is stupid and marches into melee against Reapers they could swiftly face routes on planet after planet and entire fleets turn against them.

All it takes is one person to start it all. Which is why I'm arguing why even bother with melee when your ranged weapons are overkill and would annihilate the Reapers.

This is all theoretical and damned be any fool who gets too close to them or heavens forbid space marines try board them.

"The Emperor protects."
That isn't just a fancy saying, it is a literal truth in the 40k universe. While you are correct that biological species in the Mass Effect universe have no protection from indoctrination, in the 40k universe there is the Warp and a god who does his damnedest to protect humanity.

The Emperor actively protects his followers against the powers of the Warp as a literal god. The same should be true against indoctrination. Any individual that so fervently believes that emperor, or spirit wolf, protects them like some Guardmans, many Space Marines, and especially Sisters of Battle would be protected. Things like purity seals seem to also act as channels or focuses for the Emperor's will, as purity seals have had some effect on Space Marine's ability to resit subversion. Whether this is actually due to the Emperor's will, or the Space Marine's own will reflected back from the Warp is unknown.

Orks would have a similar resistance, or greater, than Space Marines due to their gestalt psychic field, and the fact they just fight each other anyways. The biggest risk is if the Warboss is indoctrinated. However, if there is a full blown WAAAGH!! going, the gestalt psychic field should keep him on target, but your Orkiness may vary.

Chaos Space Marines would be a crapshoot. While Daemons and the like would be immune, Chaos Space Marines would be as susceptible as any Space Marine or even guardsman. Only if their patron god (unfortunately) had their eye on them, or were powerful enough in their own right, would they be protected from indoctrination, or not, Chaos is like that.

The Necron are obviously immune, and would simply walk over everyone like they tend to do.

I can't say one way or the other for Eldar, not my forte.

The Tyranid would be immune in my opinion. The will of the Hive Mind does not exist in any single biological being, nor does it wholly exist within this galaxy. Even in the Warp it is a massive hole that swallows up daemons that cross it. Trying to indoctrinate the Hive Mind would be like trying to slowly indoctrinate a single synapse at a time, of which the Hive Mind can overpower, or would take so long to even affect the Hive Mind it is a nonissue.

Tau would be at the biggest risk as they have no protecting from a Warp entity, nor the advantage of being a machine. The only hope the Tau have is being able to detect the signal with their more advanced equipment and filter it out with destructive interference.

On the tech side, Gellar Fields, with their ability to stave off some of the worst of the Warp, should be able to protect ships from indoctrination. Whether they would actually have their Gellar Fields up in combat is a different question.

Well Javiks accounts might have other interpretations, but as you say its ambiguous how fast they turned.

Its an awesome universe with tons of lore wonderful characters and races so I can't blame ya. Ending of ME3 was just to much for me, but I should give it a go again in the future.

As for Tau, and I need to point out that I can definitely be wrong about this. Doesn't the new lore kinda heavily hint that they are being (for the lack of a better word) "indoctrinated" by the Ethereals?
Like how would indoctrinate an indoctrinated work out?

Then the Emperor really needs to license some new faith pins or something because a hell of a lot of people pray to him every day and die.

Protection from warp and psychic effects. Yes. Protection from actual scientific effects? No.

Your implying the Reapers indoctrination works the same way as the warp and it doesn't. It's not a thing that exists on an emotional/faith level that interacts with the warp. It just affects biological species as easy as a bullet kills them and it is an effect brought on by the mind control technology of the Reapers that targets the brain as easily as any conventional weapon could.

So the vast majority of biological species can't resist it including Space Marines. It's one of the only things I would give the Mass Effect universe an advantage for as 40k has such overwhelming odds of winning otherwise. I know my stuff and I know that indoctrination would be an extremely big problem for any biological species. Some species ion 40k could be more resistance than others. I'm not going to deny Space Marines would resist indoctrination for longer, but would eventually succumb. Other races would last longer or shorter. Also I agree the Tau and Etherals would be extremely susceptible. Right up there with regular humans.

The Tyranids might be immune, but maybe not. It would depend on individual strains of creatures. Rachni queens born before the Reapers took over their civlization were immune to the effects, but their children were not and they are the ME closest analogue to Tyranids. The Rachni Queen that was born after though with the mind control on her when young was indoctrinated. So it all depends on how it reacts with each Tyranid creature.