He has wholly given over his existence to the art of the kill, particularly using the melee weapons so favoured by his Dark God. Masters of Executions bestride the battlefield like avenging gods of war, using Warp-enhanced senses to seek their prey.
Amidst the thunderous tumult of battle, a Master of Executions strides unflinchingly forwards, his mind focused on the gruesome decapitations he will soon administer. He is a being of singular purpose, a brutal weapon in the arsenal of the Heretic Astartes, and his existence is driven by an unquenchable desire to take as trophies the heads of mighty champions and charismatic leaders.
When he reaches the lines of the foe he lofts his enormous cleaver. Lowly soldiers are hacked apart with contemptible swiftness, their deaths providing only the most fleeting moments of joy to the executioner -- hot sprays of blood feel cold against his skin, and the screams of terror that come as his blade makes its descent ring hollow in his ears. Yet every body through which he cleaves brings him nearer to his quarry.
As the Master of Executions draws closer to the enemy's champion he bellows his fatal decree, proclaiming the enemy warrior's life forfeited to the Dark Gods. With a terrifying burst of speed, he closes upon his declared victim, crushing whatever defence they offer with blow after sweeping blow.
A final unerring swing sees the energy-wreathed axe blade carve through armour, flesh and spine without slowing. As he watches the opponent's severed flesh spinning through the air and the gushes of arterial blood that jet from the toppling corpse, the executioner feels the gaze of the Chaos Gods fall upon him.
A jolt of exaltation runs through his body, his veins crackle with empyric power and his hunger for death grows even stronger. He claims the disembodied remains of his enemy as his trophies, then looks for the next foe worthy of his fury.
Only the most single-minded become Masters of Executions. It is a calling that comes in many forms -- a Chaos Space Marine may hear a ceaseless stream of whispers telling them to seek out and behead the mightiest of their enemies, or they may see visions of disembodied skulls from which a deluge of blood drips onto the battlefield.
Others perceive the heads of their foes as repositories of knowledge that need to be prised open, or as sheaves of flesh and bone that are ripe for the harvest. Regardless of how they are called, these dark transhuman warriors cast aside all other pursuits of glory and dedicate themselves solely to murder.
Through sorcerous rituals Masters of Executions attune their murderous senses to the currents of the Warp, granting them the ability to see the souls of their foes in the Empyrean. Some even go so far as to gouge out one of their eyes to allow the empyric currents to coalesce in the raw and empty socket.
Even on the most anarchic battlefields an executioner can pick out his chosen targets, looking through the clouds of choking smoke and ranks of lesser foes towards the bright burning spirits of the mightiest enemies, marking them for death.
The deadly expertise of each Master of Executions is evident in their gruesome array of trophies. Their collection of heads speaks to the manifold enemies they have slaughtered, with skulls and helms of different foes lashed to their armour or skewered on spiked racks. The most impressive trophies are given places of prominence, while from lesser foes sometimes only a tooth or fragment of jawbone is added to the panoply.
It is not only heads, but other body parts that an executioner displays as the spoils of his labour. He might string the eyes, ears and tongue of a powerful mystic around his neck, fuse the shattered bones of a previously undefeated warrior to his wargear or drape the peeled skin of a particularly charismatic enemy leader over his armour.
Some Masters of Executions find themselves compelled by the Warp to butcher enemies from a specific species, and their trophy collections comprise the grim remnants of that species' greatest champions. Others feel the urge to slaughter a wide variety of foes, resulting in grisly displays that contain all manner of cadaverous specimens.
Within a warband of Heretic Astartes, a Master of Executions is often used to mete out punishment to those who seek to usurp the rule of a Chaos Lord. The wayward Chaos Space Marine is corralled by his brethren into a gore-stained arena and forced to face the executioner in a duel to the death.
Such contests are brutally swift, and serve to sate the murder-lust of both the warband and the Master of Executions. But a Chaos Lord must be ever wary, for while this practice helps thin out those warriors who have delusions of grandeur, the Master of Executions' axe may also come for him one day if there are no enemy champions to slaughter.
- Codex Heretic Astartes - Chaos Space Marines (8th Edition) (Revised Codex), pp. 62, 129
- Warhammer Community - Heretic Astartes Focus: The World Eaters