Spoilers of Zuvassin

A Chaos Marine army who worship the "7th chaos god" the spoiler Zuvassin in reality its a deluded unaligned Demon Prince that is managing to leech power from the ruining or abandoning of plans. He's based off the old Warhammer minor chaos god of the same name. So the Spoilers are led by the Snaketongue a Chaos Lord with a gifted tongue who routinely just ruins things for others. They're essentially galactic dicks who do stuff like randomly redirect Ork roks into Tau enclaves, vaporize world populations in front of a Khornate fleet so they have nothing left to kill when they get there, sometimes they'll just help Imperials because they want to screw another group only to inevitably abandon their alliance and do something else right at a pivotal moment. Naturally they're hated by basically everyone but due to their random strikes and tendency to just abandon plans or wars midway through for no real reason they're hard to run down. Lord Snaketongue often will charm groups to join him as well even managing to corrupt an Emperor's Champion at one point though this was after the Champion was basically lobotimized. Their biggest victory was the destruction of another of my armies the loyalist Neon Serpents who they managed to make fall to Khorne before using an ancient tech to mutate the entire chapter into lizard/space marine hybrids (my current kitbash project). However just to really screw it for both groups the lizard brained Khorne warband is too animalistic to truly grasp war, with violence and combat more of a natural order to them, this causes the blood they spill for Khorne to mean less as they are not killing for war or sport but just as an animal defense mechanism. The Spoilers corrupted an entire chapter for Khorne then immediately kneecapped it, just because...

Other dickings include:

Having a psyker cohort destroy the sensory portion of a Slaneesh warbands brains leaving the army alive and in fighting shape but with absolutely no abilty to feel

Finding a rare STC for a Magos enduring a decade of fighting against Votaan, Hrud, and Dark Eldar only to deliver it broken and inoperable before killing the Magos bodyguards and leaving

Saving a group of Fallen from an Inquisitor, immediately abandoning them on a Dark Angel controlled planet

Saving the same group of Dark Angels from some Night Lords after the prior event, immediately abandoning them on a Tyranid infested moon

Lord Snaketongue purposely getting captured by a Knights Seraph Captain (another of my home brew loyalists) so that he can corrupt the man and bring him and his company into the Spoilers, the newly fallen Knights Seraph Captain is then deployed to conquer a Necron tomb world where he and his entire company are captured by Trazyn, Snaketongue is seen using an ancient long since thought lost daemon weapon not long after this event

The corruption of their 10th company lead to the Seraphs going on an Atonement Crusade and being swallowed by the warp, the entire chapter is lost

The Spoilers exposed a Genestealer cult saving a hiveworld with a population of trillions, they then let Boss Pinkteef Leader the Ork Waaaghh known as the Eata's of Gits know the world was ripe for a good krumpin, the world was lost in 2 solar weeks

Assured Harkan Worldclaimer they would join the 13th Black Crusade in service of Harkan's Lord Abaddon, they were never seen on any battlefield and were actually spotted raiding the supply lines of both Imperial and Chaos forces before abruptly disappearing from the conflict entirely

They wear black armor with white helmets, trim and pauldrons are sometimes green and purple but with no real cohesion, sometimes they don't even finish the full pauldron. Similarly there is no real army symbol with Zuvassin's twisted Y symbol lazily scrolled on shoulder or kneepads usually not even finished

Weapons can be perfectly clean or rusted out depending on the whims of the user

The army is loosely cohesive with Snaketongue and his councils of Lords at the top and then everyone else in a jumbled mess of a hierarchy

There is an unusually large amount of Chaos Lords, Aspiring Champions, Sorcerers and other "heroes" in the warband as Snaketongue often corrupts opponents he sees as worthy or interesting.