An Aggressor, who is usually a member of an Aggressor Squad, is an Astartes fire support specialist unique to formations of Primaris Space Marines.
Aggressors are tasked with close-range fire support and have been outfitted with modified Mark X Gravis Power Armour refitted suits to carry a shoulder-mounted Fragstorm Grenade Launcher.
They also wield Flamestorm Gauntlets that unleash blazing streams of promethium upon any foes that get in close -- or can be used to wade into the mobs of the enemy and unleash an inferno that burns them all to ash.
The Space Marines in a Chapter's fire support squads have a vital role, covering fire to their battle line and close support brethren. This could be in the form of the assassination of prime targets, counter-battery volleys, or the destruction of enemy armour. Their target selection, marksmanship, and timely application of firepower are countless battles won.
Clad in heavy Mark X Gravis battle-plate, Aggressor Squads advance upon the foe as walking fortresses of ceramite. Each member is equipped with a pair of Boltstorm Gauntlets, meaning an Aggressor Squad can lay down a hail of bolt fire.
Aided by back-mounted Grenade Launchers, an Aggressor Squad can wade into oncoming enemies, mowing a bloody path through even the most immense hordes. Should a foe have enough bodies to sacrifice so that living members can finally reach the source of the onslaught, they are met by Space Marines swinging paired Power Fists. Very few live to tell the tale.
More mobile than the heavily armoured Centurions due to their sophisticated Gravis armour, Aggressors are better able to negotiate rough ground. This makes them a more versatile troop type; while they are often employed in specific circumstances or on a particular terrain, Aggressor Squads are also used as reserves to plug breaches in gun lines or to spearhead an advance.
In dense environments, such as within a hive city or under the canopy of a forested area, Devastator Squads would find their long-ranged weapons of little value. Such terrain suits Aggressor Squads to a tee, as they are ideally suited to firing on the move. The range of their weaponry is not long, but when they get close enough to open fire, the result is a sweeping fusillade of large-calibre Bolter shells that can shatter enemy charges.
For incredibly dense terrain, or when facing foes that cover the ground in significant numbers, Aggressor Squads will wear paired Flamestorm Gauntlets. When equipped this way, their armour's raised shoulder guards protect against the inevitable flame backwash as they stride forward, their arms sending sweeping arcs of fire billowing out.
The fire flickers like a hellish wreath about their armour as the Aggressor Squad advances, their weapon barrels glowing like embers in the smoking gloom. Ork hordes and Tyranid swarms alike are incinerated, their brittle and blackened bones crackling to dust underneath the tread of the Aggressors as they march straight into where the fighting is thickest. Some have said the Aggressors live for such moments and dwell over-long upon them.
Since being introduced during the Ultima Founding and Roboute Guilliman's reworking of the Codex Astartes after his resurrection in 999.M41, the Aggressor Squads have proven themselves as a devastating force many times over.
