Adeptus Mechanicus Skitarii
Harnessing the destructive energies of forge worlds within their weaponry, the Vanguard are so soaked in radiation that even to approach them is to confer a death sentence upon yourself. Victory for them is pyrrhic, as this radiation burns through even their heavy armour plate, slowly poisoning them to death even as their carbines bring about the(much quicker) demise of their enemies.
Skitarii Vanguard, featuring helmets and rebreathers, obliterate foes with radium carbines. Each trooper is sealed in heavy, industrialised Skitarii warplate, emblazoned with the symbol of the Adeptus Mechanicus, bristling with data-collecting sensors, antennae and environmental monitors. Mindful of the harsh terrain of Mars, their legs have been removed from the knees down, with bionic replacements lending each model an air of cold, cybernetic augmentation