Well, only one day late...my best mark. Anyway...
Alvaur Cravasson everyone, also called "Roar" because of the way he likes to begin every assault on a city/ship/fortress. Poor Cravasson, it's not that he actually does it on purpose, the "roar" is actually his cry of agony once the drugs in his back-mounted vials start flowing through his veins. Drugs akin to those the Eversor used, but warped by Chaos - but mostly full-on daemonic blood.
But let me tell you his story.
Cravasson had long been the Raptor leader in service of Krieg Acerbus when he encountered Brother Corbulo of the Blood Angels on the battlefield of Tethraz. A great warrior too arrogant for his own good, Cravasson (at the time donning a richly detailed armour of midnight and bronze with the Atramentar lion head on the shoulder plate) underestimated the Sanguinary Priest and got a shot to the face for his mistake, courtesy of Corbulo's Carnifex (it's a pistol-like device all Apothecaries possess).
Acerbus saw the opportunity in this. Cravasson had never been the most staunch supporter of his "fear as an end" philosophy - although his loyalty was as unquestionable as a Night Lord could provide -, and here was a chance to make a shining example for all the Warband to see. A visit to Fabius Bile later, the Raptor had gone from being at the edge of death to being at the edge of sanity, now transformed into a drug-fuelled nightmare and a psychotic parody of an apothecariy, Fabius having binded adamantium-tipped syringes, piston-powered spikes and Cravasson's own twin chainswords in what he dubbed a Morthecium.
No more richly detailed armour for Alvaur Cravasson, now. No more thinking about the ways of the Legion. No more underestimating. Now, all that Alvaur Cravasson sees beyond the red-tinged screaming masks of death of his enemies, are the faces of warp-denizens too great for him to comprehend, their laughter running through his veins as he rushes to the next kill.