Relishing in their brutality and savagery, the World Eaters were among the first legions to betray the Emperor and join in service to the forces of Chaos. Cybernetically enhanced to bring out their vicious fighting abilities, the "Butcher's Nails" implants allow these Traitor Space Marines to become forces of nature unto themselves. Devolving into warbands from their united Legion, they nevertheless spread the bloody worship of their Chaos God Khorne through destruction and death.

Raised in the deadly gladiatorial pits of Nuceria as an enslaved fighter, the former Primarch Angron was augmented with the dreaded "Butcher's Nails" before being rescued and returned to the Emperor's side. Seething with hatred towards the Emperor for failing to rescue his brethern in the arenas, Angron was amongst the first to turn to Chaos once his brother Horus began his unholy crusade. Transformed into a Daemon Prince, he brings upon the Imperium of Man nothing but savage butchery and death as he falls upon the galaxy like a plague in the service of the Chaos God, Khrone.