The Emperor Falls.

Part 4/? - A Blood Daemon rises.

The Emperor, even in his deathless state and years of withering, can still react within milliseconds. He moves his head back, narrowly avoiding the Spear of Telesto coming toward his face. He looks upon Sanguinius' face. The Flaw, the Black Rage has all but taken over. This is it. Horus himself knew that Sanguinius under this flaw could destroy any and all who opposed him. He raised his blade and began to defend his strikes. For the first time in millennia, he felt an emotion that wasn't insanity, rage, fury and depression. He felt remorse. He couldn't kill his son like this. He had to convert him, he had to stall for the Black Rage to run it's course. 

Magnus opens his eye, witnessing the ensuing battle, he attempts to intervene however Alpharius and Omegon await him. Using his psychic powers he informs his father that he is awake and that Alpharius and Omegon are attacking him. The Emperor simply states that he must stall for time. Magnus, through the warp, calls upon his legion, the Thousand Sons. They march out and are ordered to gun down the Twins. Bullets fly as they are hunted. He does not understand Sanguinius' betrayal, but his Father seems to. He'd heard rumor of a flaw, perhaps this was it. Perhaps he was waiting for it to revert, that's why he was stalling. 

He reaches the Twin Primarchs, ordering his men to execute them. With ruthless efficiency, Alpharius cuts down the Legion while Omegon peppers shots at Magnus. Alpharius, picking up a dead Thousand Sons Marine, throws it at Magnus, knocking him down. Omegon reaches him and stomps upon his chest. Believing him to be dead, he turns, unable to notice the large energy pulsating from behind him. Magnus destroys Omegon entirely and plunges Alpharius into a rock, breaking his back. 

Sanguinius, having swapped to his blade to better combat his Father, begins a final assault. He charges, shoulder barging the Emperor, knocking him down before plunging his blade into and through his armor, through immense effort. He stands over him. A final message reaches Magnus, "Destroy him." It is cold and ruthless in tone, but his father's voice nonetheless. He begins charging a psychic lance, one of such power not seen since Horus' defeat. The throw is wound up, before releasing. He hits his target. Sanguinius' soul, being pulled towards the Chaos God's but another aswell. The Emperor. The lance had struck Sanguinius through the chest, and skewered the Emperor through the chin. While his corporeal body lives, his soul is being siphoned from him. If it reaches the Gods, they can destroy it and thus kill his body. It is only due to His pure will and strength that he holds Sanguinius' soul and his own in place. Alpharius however, has a better plan. His shot lined up, he blows through Magnus' eye, killing him instantly. The psychic shockwave knocks everything back, Sanguinius' soul is freed and the Emperor's soul barely manages to hold itself steady. Magnus' soul immediately rushes toward the Emperor's and they combine. Sanguinius is pulled into the Chaos God, Tzeentch's embrace and disappears from the Warp.

The so-called God-Psyker soul combination tears through Daemon and Marine alike before reaching Alpharius. Alpharius, in his last moments, explains to his Father how Omegon was still loyal, and even why they had turned. "As was planned, what you know as Horus' Heresy, was simply a plan on a regicide board. I didn't plan for Horus to turn, nor for Fulgrim and Magnus but I knew I would have to separate the wheat from the chaff.  Similar to my plan with the Thunder Warriors. You were tools. You were my sons like the Earth was a son of Mother Nature, by creation only, not by blood nor love." Alpharius hears this before he is erased from existance. Tzeentch has failed, his trickery and planning, his own folly. he must now regroup and begin the final march on the Anathema.

It is then however, Tzeentch realises something. He can feel the Webway's presence here. If only he could pierce the wall, he could then get to the Webway Gate on Terra and destroy it and the Emperor. If only he had a powerful psyker. One on the level of a god. It is then Tzeentch smiles, gleefully, for he has exactly what he needs.