Baron Vardus Praal was the Imperial Governor of Istvaan III in the times of the Great Crusade. It is know that he eventually fell to the temptations of the Pleasure God Slaanesh, along with the majority of the planet's indigenous people. Warmaster Horus Lupercal, now newly corrupted by the insidious Dark Gods, would utilise the rebellion as a means to rid himself of the Loyalist elements that remained within both his own Sons of Horus, as well as three other Space Marines Legions under his command -- the Death Guard, Emperor's Children and the World Eaters. It is believed that the Traitor Vardus Praal died in the saturation bombardment by the Traitor Legion ships, when the Warmaster ordered the deadly virus-bombing of Istvaan III.