The Last Chancers
Amongst the Imperial Guard, Unique regiments consisting of convicted criminals of all stripes and shades who have avoided execution or a grim future in the form of a servitor, only to be pressed into penal legions alongside thousands of others for a chance to absolve themselves of their crimes though suicidal acts beyond those of normal guardsmen. Either though serving their sentence or being cleared of charges posthumously, A penal legion almost guarantees the innocence of an individual if they refrain from fleeing, but a messy, gribbly end awaits those who flee from battle or try to escape confines during transit, normally administered by an explosive collar or a bolt pistol.
Yet again, amongst the many thousands of penal legions reside the thirteenth penal legion, while not being the thirteenth legion to be formed, they are however legendary amongst the guard for being a virtual death sentence, even other penal legions see those residing in the thirteenth as lost causes. This dread reputation a direct result of Colonel Schaeffer being the most heinous and downright evil imperial guard officer to ever exist. There is a high chance men under his command will die before reaching the frontlines, normally a direct result of forced marching along the quickest path en route to the frontline, normally footslogging though "hazardous" environments, luckily death = an easy pardon, so it's not all bad.
The Last Chancer series follows legionary Lieutenant Kage as he shoots, stabs, strangles and shouts his way through a brutal sentence serving under Colonel Schaeffer in the Last Chancers as he leads the thirteenth penal legion on suicidal missions across the galaxy. Consisting of three major novels, 13th Legion-Kill Team - Annihilation Squad and a scattering of short stories, Deliverance - Liberty.
Probably one of the more interesting Imperial Guard legions in that they actively question authority and say a lot of heretical things without worrying about Commissars or Commanding Officers executing them every five seconds. They are the Last Chancers and they are lucky to be alive.
History
Last Chancers were created for a special assignment 2.5 years in the making. The Inquisition needed to clean up a big mess they made in a highly populated Imperial city. Instead of blasting the planet to kingdom come with any Planet crackers they had, they thought they could use an elite special forces team to break in side the heavily defended city. Instead they got a bunch of cut throats and killers that would gladly kill their own mothers for a pardon for their crimes.
The Last Chancers are in most ways a publicity stunt that has backfired. Most people see them as god damn heroes even though they are told they are nothing but cannon fodder.
13th Legion
We start by being behind the eyes of a man who is not Kage, entering a lab and finding the "experiment" he was overseeing has, at some point in the past, wandered off, at which point he comes to the conclusion