As the Horus Heresy raged on, Horus fell further and further into the grasp of a dark and terrible malaise. Where once he was a paragon of honour, renowned for his sense of justice and camaraderie, he became grim of aspect and ever ready to dispense fearsome punishments for even the most minor of infractions or failures. As his temperament grew darker and more bitter, his body slowly transformed. Bloated with dark power, he now towers over even his Primarch brothers, possessed of a strength and resilience that no living man, save perhaps only the Emperor himself, can match.