Reborn

After the Horus Heresy many millennia when the legions were split and soon now the imperium knowns only war. The emperor now entombed on the golden throne. Saw a certain legion of his son who are not giving up on the imperial truth and fight on. The emperor uses his immense power to get his son back reborn in a far of world named Remnant. How will it react when the reborn Primarch of the 21st legion.