- "When one requires the divine sanction of every heretic or daemon within an assault zone, accept no alternative to the Purgation Squad."
- — Inquisitor Ordale
A Grey Knights Purgation Squad is a formation of specialised warriors that is unique to the Grey Knights Space Marine Chapter. Purgation Squads are the Grey Knights' foremost means of delivering punishing firepower. Each squad carries not one, but up to four of the Chapter's heavy weapons. In aspect, a Purgation Squad appears little different from the Devastator Squads employed by more conventional Space Marine Chapters. In doctrine, however, the two are markedly different. The weaponry wielded by a Purgation Squad is twice as deadly, a hundred times rarer and ten thousand times more valuable than the more commonplace armaments carried by Space Marine Devastators. Devastators will normally advance behind the main assault, seeking out suitable locations from which to unleash covering fire; Purgation Squads are required to keep pace with the main attack, all the while picking out suitable targets for their weaponry.
- "Let my brothers practise their swordplay. They can finish off whoever is left."
- — Purgator Rocht Kavanar
The Grey Knights are as varied as any of the Imperium’s Space Marine Chapters and include in their numbers specialised warriors to deal with a myriad of combat situations. Many of these, such as Techmarines and Librarians, are organised and trained in much the same way as they would be in other Chapters, following the ancient guidelines and traditions laid out in the Codex Astartes. Others are unique to the Grey Knights and only found within their ranks, such as the Grey Knights Strike Squad, which is specially trained and equipped for a task specific to the Grey Knights' eternal war against the Daemonic. While most Astartes fight in wars, launch raids, and engage in other traditional military actions, the Grey Knights Chapter is specialised in responding to daemonic threats with only a moment’s notice, ready for battle, and ending the threat quickly before it can damn entire planets.
In the Grey Knights, the Purgation Squads fill the traditional heavy weapons role normally carried out by Devastator Squads. Like a Devastator Squad, a Purgation Squad carries heavy weapons into battle and targets powerful enemy adversaries, emplacements, and war machines. In most Chapters, duty in a Devastator Squad is seen as an excellent opportunity for a new Initiate to experience the sights and sounds of a battlefield. Not so in the Grey Knights. Unlike Devastators, the members of a Purgation Squad are entrusted with weapons far more valuable and specialised than those more commonly brought to war by the Adeptus Astartes. These include weapons specially designed to fight daemonic and psychic foes such as Psycannons and Incinerators, a form of Heavy Flamer that makes use of sanctified Promethium, which a Purgation Squad member must know how to use to their greatest effect. They must have both a deep knowledge of daemonic foes as well as an intimate understanding of their weapons’ capabilities and limitations. Therefore, the members of a Purgation Squad must, if anything, have displayed an ability and resolve beyond that of their peers. A Grey Knight must prove both his worthiness and his skill at arms before he is honoured with the right to carry such potent weaponry. Furthermore, whilst Devastators will normally advance behind the main assault, seeking out suitable locations from which to unleash covering fire, Purgation Squads are required to keep pace with the main attack, all the while picking out suitable targets for their weaponry.
The Grey Knights appreciate that precision fire support can swing the fortunes of war, and so a Battle-Brother who earns a place in a Purgation Squad will not only have shown his steadfastness, but will also have proven himself to be the master of a keen eye and a steady hand. Yet sometimes a keen eye is not enough. Fate often ensures that the Grey Knights go to battle greatly outnumbered, and warriors outnumbered are prone to being overwhelmed whilst their attention is elsewhere. So it is that those Battle-Brothers who serve in a Purgation Squad hone their minds to see through the roiling energies of the otherworldly Warp, to perceive the foe and guide their shots upon him, regardless of what might lie in between. This astral vision allows a Purgation Squad to attempt seemingly impossible shots, bending the path of projectiles and even energy beams around corners, between trees and around fortifications mid-flight. Many an enemy has met a swift and bloody end whilst believing himself shielded by a rockcrete wall or the burnt-out hull of a tank. So it is that Purgation Squads are commonly seen as the truest expression of the Emperor's Will, for their onslaught cannot be stayed by earthly protections. Once his duties are established, it is rare for a member of a Purgation Squad to see service elsewhere in the Chapter. A ranged battle stance, once mastered, is not easily set aside for blade upon blade tactics -- indeed, those Grand Masters and Brother-Captains who once served in Purgation Squads are easily indentified, as they continue to wield a Psycannon or Psilencer -- the weapon that long ago became as much a part of their being as their own right arm. Those Grey Knights officers who do eventually set aside their heavy weapon for a Storm Bolter can be ranked amongst the finest shots in the Imperium, for the skill of a Purgator is one that never truly fades.
- Aegis Power Armour
- Wrist-Mounted Storm Bolter
- Psycannon - There are perhaps only a few score Psycannons in existence at the close of the 41st Millennium. Many have been lost or destroyed since their creation in the Dark Age of Technology, and the secret of their forging has long since been a secret of the past denied to the Imperium. Those Psycannons that have endured the passing aeons now remain in the custody of the Grey Knights. Only they, of all Mankind's defenders, have sufficient strength of mind and will to activate the psychically-charged payload which can prove so devastating to Warp entities. Most Psycannons are relatively compact weapons, and can be wielded in battle by a single Grey Knight.
- Psilencer, Optional - A Psilencer fires nothing less than the focused and amplified psychic might of its wielder. The Psilencer does not have a triggering mechanism as such -- it is activated when the Grey Knight sends a bolt of psychic force into the weapon's containment core. The resultant energy pulse is then channelled by a series of focusing crystals into a refined beam of irresistible azure force that has a particular propensity for destabilising a daemon's physical form. It is unknown how the Psilencer came to become part of the Grey Knights' arsenal. The technology is surely of alien origin, for it is unlike almost anything else that can be found in the armouries of the Imperium. Yet was the Psilencer constructed from technology stolen, or technology given freely? The Grey Knights remain silent on this matter.
- Incinerator, Optional - Many a Grey Knight holds cleansing flame, and thusly the Chapter's Incinerator weapons, to be foremost amongst the many weapons in the Chapter's arsenal. An Incinerator is a heavily modified variant of the Heavy Flamer, its fire projectors and containment vessels significanty altered in order to accommodate psychically impregnated Promethium fuel. When triggered, the weapon gouts forth an incandescent torrent of azure flame that burns far hotter than any "normal" combustion ever could and which wreaks fearful havoc on daemonic flesh.
- Psybolt Ammunition - Purgation Squads know that while their weapons are priceless artefacts, they are also some of the best and most powerful weapons available for destroying daemonic and psychic enemies. They have learned to activate Psybolt ammunition in their weapons with their own psychic potential.
- Nemesis Force Sword
- Frag Grenades and Krak Grenades
- Psyk-Out Grenades
- Liber Daemonica - The Liber Daemonica is an enduring symbol of the Grey Knight's devotion to his mission, and contains the cardinal tenets of lore culled from the dark knowledge caged within the Sanctum Sanctorum's walls. Every Grey Knight carries a copy of the Liber Daemonica in a Ceramite case on his breastplate. These gnarled tomes contain the Chapter's rites of battle and detail the traditional duties of every Grey Knights' rank. The books themselves are also potent psychic talismans in their own right, with pages illuminated in silver and bound to a spine carved from the thigh bone of a martyred saint.
- Astral Aim - Marshalling ancient sorceries, a Grey Knights Purgation Squad can mystically guide their shots to the chosen target. Little is hidden from the penetrating gaze of a Grey Knights Purgation Squad. The Grey Knight extends his senses and possibly those of his allies to peer though the Empyrean itself, picking out foes hidden from sight or behind concealing cover. Those affected by Astral Aim can shoot targets they would not normally be able to see, such as through walls, in complete darkness or through shrouding mist.
- Hammerhand - Focusing the raging power of their minds, Grey Knights can augment their already prodigious might. Even unarmed, such a warrior can crush flesh and bone -- given blade or warhammer there is little limit to what they can slay.
- Codex: Grey Knights (5th Edition), pp. 29, 57-58
- Dark Heresy: Daemon Hunter (RPG), pp. 124-125