Quick 40k lore question:

What do we know of as the ultimate weapon out there in the galaxy? I'm talking be all and end all. Weapons of impossible devastation capable of wiping out billions in a few simple shots.

As far as I know the Imperium have things like Cyclone Torpedos and Virus Bombs for wiping out planets with Exterminatus but I also read that Chaos have/had the Planet Killer and the Armageddon Gun or possibly the weapons on the Blackstone Fortresses in addition to some of the previous. From what I read the latter also sent a star into supernova with enough of them.

Tau I know have Icefire/Darkstar Warheads and their high yield plasma missiles from Achilus assault to bomb the places back to the stone age.

Question is though, are there any other superweapons out there capable of such planet wrecking or even system destroying power with some of the other groups?

The original Necron Codex described the War in Heaven as being one where black holes were used as strategic level weapons. One imagines that Old One/C'Tan/High Level Necron tech is fairly rich in weapons capable of destroying entire worlds. C'Tan themselves are said to have a natural form that consists of plasma spread over thousands of miles; arguably a C'tan in its natural form would therefore be lethal to many planets.

According to the most recent Dark Eldar Codex, the Dark Eldar use ancient captive stars to power Comorragh: this suggests they had at one point the means to move them into the webway and lock them in position. If you can move them in to the webway, you can conceivably move them out . Imagine a dying sun fired from a sufficiently large webway portal: that would be pretty lethal to anything in its path.

Hrud migrations, according to the Badab War books, are also pretty lethal. They appear to manifest suddenly in vast numbers using entropic weaponry. The Star Phantoms were almost wiped out by such a migration, and I believe their entire fortress monastary was destroyed, a feat which is close to exterminatus class weaponry.

The Tyranids routinely in effect destroy entire ecosystems, leaving the actual planet as bare scoured rock. This arguably makes the Tyranid hive fleets themselves a type of exterminatus class weapon.

I am discounting tyranids since they are not so much one single weapon or device but a collection of creatures...even though it is technically the hive mind.

I read somewhere about the Necrons having some sort of star map capable of snuffing one out with ease. Any further validation on this?

Essentially I'm trying to discover what each race has as a nuclear option, their end game weapons for MAD style scenarios.

Yes the Necrons have the Celestial Orrery

http://wh40k.lexicanum.com/wiki/Celestial_Orrery#.U4IhtSiaW8A or page 15 of the necron codex

I'm sure I missed some, but the list I can think of are as follows:

Sun-Killers:

Multiple Linked Blackstone Fortresses (Battlefleet Gothic)

Celestial Orrery (Necron Codex)

The Nightbringer's Flagship (Implied, timespan unknown, Nightbringer )

Planet Killers:

The Planet Killer (unsurprisingly, Battlefleet Gothic)

The Fireheart (Eldar/Dark Eldar Doomsday Weapon from Valedor )

Black Cube ( Legion , chaos relic) - correction. John Grammaticus says a safe distance is "The Edge of the System"...

Biosphere Killers:

Virus Bombs (Imperial, multiple sources)

Cyclonic Torpedoes (Imperial, multiple sources)

Exterminatus Array ( Warrior Brood - Massed Energy Weapons of non-specific type mounted on a battle barge)

Magna-Melta Orbital Bombardment Warheads ( White Dwarf , Imperial)

Single Blackstone Fortress (13th Black Crusade)

Tyranid Splinter Fleet (Multiple sources)

Directed/Summoned Warp Storms (Multiple Sources)

Suprisingly the Orks don't seem to have any truly massive weapons of mass destruction.

Of course there's always the hope that one day a mek will get the idea for "Gorks own gun" :A canon so vast it can one shot planets. Or a shock attack gun the size of a spacehulk that can rip out a planet's core as if it were an apple.

Or a bubble shuckka that can envelope an entire planet... wouldn't tat be awesome?

Don't forget the necron mega weapon on Cadia. Its capable of completely separating the physical universe from the warp. If ever activated would wipe out every living thing tied to the warp.

Oh yeah that

Don't forget the necron mega weapon on Cadia. Its capable of completely separating the physical universe from the warp. If ever activated would wipe out every living thing tied to the warp.

Oh yeah that's right, it would rip our souls out of our bodies. Maybe the Tau could hang in there since they have so little presence in the warp...

Can we count made up ones?

Can we count made up ones?

Such as...?

I think Orks would do something like this

From Planetary Annihilation , small planet that has been fitted with huge rocket engines.

This is what happened when it hit other planet

That reminds me of one of the Horus Heresy space wolves novels. They captured what was basically the death star and crashed it into the planet it was orbiting. Even their imperial army allies were like "that's a bit much isn't it?"

Well, the Orks do routinely go around in huge, more or less hallowed out asteroids, intending to land or crash them on random planets. Last time I checked, asteroid impacts of sufficient size where extinction level events, and it's not like the Orks care if they lose a bunch of boys in the process.

The Necrons and the Eldar most probably also have a whole bunch of ridiculous weapons of mass destruction from the War in the Heavens laying around, mostly based on creating black holes/dimensional tears and manipulating stars, with the Necrons also having a bunch of anti-warp and soul sucking ones. However, the Eldar probably lost some of them in the meantime, and might have forgotten how to use those they stashed away in places like the Black Library; your real problem is the Necrons, since all the Necrons today are the same exact ones that fought the War in the Heavens; sure, some of them might have memory problems, but the Cryptek conclaves who built those weapons are still kicking around, and pissed off to boot because the Eldar aren't dead yet.

Can we count made up ones?

Uh...it's all made up.

BTW There are plenty of crazy spells that can open a rift to drag millions of screaming deamons into the physicial world...that's got to count right?

That reminds me of one of the Horus Heresy space wolves novels. They captured what was basically the death star and crashed it into the planet it was orbiting. Even their imperial army allies were like "that's a bit much isn't it?"

and it turned out to be a scientific repository pissing off everyone that they broke it. lol

But we're forgetting the one planet killer available to players. Vortex of doom as written in DW will likely destroy the whole universe over time. Since the odds of growing are greater than the odds of shrinking, it has a 72% chance of reaching 100 meters instead of disappearing at which point its basically guaranteed to eventually get the whole planet.

The answer is a marine and his bolter.

Bah weakling second founding chapters! World Eaters need no guns! Me crush you with my bare hands!

rip and tear! rip and tear! blood for the blood god!

The answer is a marine and his bolter.

That old chestnut.

The answer is a marine and his bolter.

No, Its an imperial guardsman with a lasgun.

The answer is a marine and his bolter.

No, Its an imperial guardsman with a lasgun.

Ah yes, death by laughter as the flashing light tries to disorientate them!

The answer is a marine and his bolter.

No, Its an imperial guardsman with a lasgun.

Ah yes, death by laughter as the flashing light tries to disorientate them!

No the moment where the khorne berserker gets a sprain in his arms from chopping up guardsmen all day, is so sick and tired of killing guard by the dropship-load that he and his buddies go back to the eye of terror to unwind and complain how guard high command is more brutal and uncaring than the blood god.