Mephiston
Mephiston is the chief librarian of the Blood Angels Space Marine chapter. He bears the title "Lord of Death" for A FUCKING REASON! He's a monstrous creature in artificer armour and his sole purpose in life is to RAPE you in close combat. Once upon a time he was just a regular joe called Brother Calistarius, a librarian of the Blood Angels. Y'know, just your average 8ft tall, super human, killing machine with magic powers and vampire-ish tendencies. So... just one of the guys, nothing that special. Then one day he was overcome by the effects of the Black Rage
Once a marine is overcome with the Black Rage he is inducted into the Death Company. Death Company marines are bat-shit crazy, berserker, vampire, space marines. Since there's no cure for the Black Rage the only thing that can be done for them is to use them as shock troops and throw them onto the front lines of the most brutal, meat grinder, suicide assaults and let them find a glorious death on the battlefield.
During the second war for Armegeddon Brother Calistarius was used to assault the Orks holding up in the Ecclesorium building of Hades hive. As he and his fellow bat-shit crazy, berserker, vampire, space marine brothers in the Death Company hacked, slashed and raped their way through the Ork defences they 'might have got a little bit too enthusiastic.' As they brought the entire fucking building down on their heads.
Calistarius was they only one left alive, buried in the rubble with his body crushed and broken. Trapped, prevented from finding his glorious death and unable to vent his rage by raping the shit out of the enemy, he was just forced to sit and stew in his fury for seven days and seven nights. The madness of the Black Rage was tearing at his mind, screaming for blood and death, causing him to trip balls with out-of-this-world, fucked up visions that had driven all before him right off the deep end!
With no where to go and nothing to do, he had no choice but to stare down the visions and fight the madness. At midnight of the seventh day he finally over came the Black rage and was re-born as.... Mephiston, Lord of Death!
Having done what no Blood Angel had EVER done before by overcoming the Black Rage he was reborn with new strength and power like nothing he had ever felt before. Feeling the utter RRAAAAAGGGGGGEE! and fury of the new born Mephiston the 1,000 tons of rubble that had been crushing down on him and keeping him trapped SHIT ITSELF (How does rubble shit itself? Mephiston was angry with it, that's how!) and tried to escape, allowing Mephiston to burst free.
As he burst free he attracted the attention of a near by Ork band. Now, there were several hundred, heavily armed Orks and Mephiston was alone, his armour was shredded, he had no weapons, and was exhausted after what had just happened. Given all this it's clear Mephy wasn't really at his best and the odds were stacked against him so it's fairly obvious what happened.... He fucked them right up! He butchered them, tearing them apart with his bare hands. He grabbed a hold of the biggest Ork and PUNCHED A HOLE THROUGH HIS CHEST AND TORE OUT HIS HEART. Then skull fucked him while the other Orks just watched and cried girly tears of fear and defeat!
After this, because of his awesome power and the fact that the other Blood Angels were a bit scared of him and wouldn't refuse his application for promotion when he applied for one, he quickly rose through the ranks to the position of Chief Librarian.
...
And this, gentlemen, is what Matt Ward faps to every night. Including the spelling errors. Mephiston, his background and his status as the Blood Angels' CC rape machine, with the stat line of a monstrous creature were already established long before our "spiritual liege" ever got his hands on the BA codex. However, Mephiston did suffer (benefit?) from Wards fetish for cheesing out codices with game breaking levels of over powering by buffing up his stats slightly to even more rape-tastic levels.