Changes

Stunned, the Thousand Sons effectively withdrew from the Crusade, returning to Prospero. It was during the period that followed that Magnus discerned the approach of the [[Horus Heresy]] and employed both his own powers and that of his senior legionaries to try to save [[Horus|his brother's]] soul. Failing, he once again marshalled the powers available to him and attempted to psychically warn the Emperor of his favourite son's betrayal. News of a sanction fleet, meanwhile, had previously reached the ears of the now-corrupted [[Horus]] himself. Sensing an opportunity, the [[Warmaster]] contacted [[Leman Russ (Primarch)|Leman Russ]], commander of the fleet, during the trip to Prospero. Speaking with his brother, he was able to convince him that "to return Magnus to Terra would be a waste of time and effort", in direct contradiction of his orders. Horus confirmed to his traitorous council of war that he believed this interjection of his into the Emperor's own decree would result in Magnus never leaving Prospero alive.{{Fn|31}} This action, which went so catastrophically wrong, would doom the Thousand Sons, as, in accord with the Judgment of Nikea, the Emperor visited destruction upon Magnus and the Thousand Sons in the form of [[Leman Russ]] and his [[Space Wolves]].{{Fn|1}}

Magnus had realised his grave mistake in warning the Emperor in the method he chose, and had also been confronted with the stark reality that he was not as in control of the [[warp]] or his powers as he thought. Additionally, a [[Tzeentch|power of the warp]] had spoken to him, revealing to him that Magnus had been its pawn since the time it had helped him save his legion from the flesh-change...and perhaps even long before that. [[file:1KSonburning.jpg|thumb|right|200px|The Burning of Prospero{{Fn|71b}}]] Distraught, Magnus resolved to accept whatever punishment the Emperor saw fit. Thus, to prevent his legion from defending Prospero, he dispersed the Thousand Sons fleet from orbit, shut down the orbital defences, and wrapped his homeworld in a 'psychic cocoon' which prevented anyone from communicating or using their powers beyond its boundaries. Thus, the Space Wolves managed to attack Prospero completely by surprise. The Thousand Sons legionaires themselves, however, did not share Magnus's acceptance of defeat and punishment, and so took up arms against the invaders. The Thousand Sons managed to hold [[Tizca]] (the only surviving city on the planet) for a period of time before they were eventually pushed back, the assault of the Space Wolves, led by their primarch, as well as forces from the [[Sisters of Silence]] and the [[Adeptus Custodes]], proving too much. Magnus eventually joined the battle when it appeared that the final moment of extermination for his legion had arrived. [[Leman Russ(Primarch)|Russ]] engaged [[Magnus]] in a devastating duel in which [[Leman Russ|Russ]] was ultimately victorious. In response, [[Magnus]] finally, consciously gave in to [[Tzeentch|the daemonic voice]] that had been tempting him and invoked ancient sorceries in order to escape Prospero with the remnants of his legion. In the [[Eye of Terror]], a [[Daemon World]] had been prepared for them by [[Tzeentch|their new patron]].{{Fn|3e}}