Mephidast

Mephidast is a Daemon Prince of Nurgle who is also known as Mephidast the Plaguereaver. He proudly bears the title of "Artisan of a Thousand Plagues," and usually commands a powerful Chaos warband composed of Plague Marines, daemons of Nurgle and Chaos Cultists of the Plague God.

History
The legends say the Artisan of a Thousand Plagues was born of mortal flesh many standard centuries ago on a human vessel seeking refuge from the calamitous eruptions engulfing the planet Verronus. Ominous flickerings in the Gellar Field heralded his birth aboard the fleeing voidship, but otherwise Mephidast's was a benign childhood spent amongst the agrarian folk who his familial tribes settled among. As he grew so did reports too foul to ignore of mutilated carcasses, and blighted crops. He claimed to be practising as a medicae, but these excuses met with hostility, and after he poisoned a local gathering festival, he was finally locked away in the depths of a primitive dungeon.

It was there that he found what he truly desired -- an appreciative patron. Endless time passed as his soul stared inwards and grew as rancid as his cell. He had only himself to amuse, and began to scrawl diagrams on the walls from his imagination, drawing on thoughts not totally his own. Shapes of unnatural angles and runic glyphs of profane languages were traced out in the unclean liquids and filth around him, blood and bile and other substances marking patterns that seemed just outside his comprehension. His body grew gaunt and tough as skin turned to leather, his hair falling away in straw-like threads, yet his devotion somehow began nourishing his unhealthy body.

Over time, the influence of his corruptive nature rotted away the bars of his cell into decrepit rust. He was free to contaminate and blight the land at will, and he set to doing so gleefully. In a solar day, the first victims fell ill. In a solar week, the dead piled up in the streets, local medicae unable to deal with the illness. His patron was satisfied, and made him more gifts so that he could carry Nurgle's blessings across the Jericho Reach. He renamed himself Mephidast the Plaguereaver after this first successful display of power, and left his now-dead home planet for greater places to bestow Nurgle's gifts.

Mephidast had no need for conquest; spreading the influence of Nurgle was his goal. He nurtured infestations of ravenous insects and created scores of Plague Zombies within huddled hive-masses. He even lured a particularly critical Adeptus Ministorum preacher to his doom in a taunting ambush, where his flesh was made unclean and rendered down into new Blight Grenades. His followers grew into a massive Chaos warhost and his goals became even more ambitious, now also striking out against any who would gainsay his patron god. It was his victory deep within the Hadex Anomaly over an entire legion of Khornate Bloodadepts, their armour decaying away as their flesh weakened and muscles grew infirm, that saw his final elevation to daemonhood. The tide of decay fell across the enemy in unstoppable waves, dissolving them to putrescent skeletal remains. He claimed the planet as his own; this victory gaining his ascension to daemonhood. His body became bloated with Nurgle's blessings, surging in scale and power. Even the Plague Marines in his retinue fell to their knees in worship.

Now immortal, Mephidast focused on plans that might take solar decades to unfold, each act growing more intricate and subtle but still with wondrously noxious effects. He has grand plans for the Jericho Reach, and the Achilus Crusade has begun to interfere with them. He is clever and patient, but his temperament is growing shorter as the time spent quenching this invasion by the servants of the Corpse Emperor reduces the time for him to achieve his true goals.