Baal'zurre

Baal'zurre, as with all demons of this world, come from the Abyssal Realms - an alternate land of shifting masses where ice burns and fire freezes, where the laws of nature are turned on their head and all but the hardiest of men will degenerate to gibbering messes of insanity. The Abyssal Realms are in constant turmoil from all the various demonic powers that fight a ceaseless war over dominion.

Baal'zurre is a Plaguespreader, a vast Greater Demon of plagues and disease. Like much of his kin he is made of the stuff of mortal nightmares, and came into being at the start of the world. Throughout history he has enacted plans to break through and conquer the mortal world, laying traps and coercing cultists to spread disease and filth in his name. Such is his vile visage that ordinary men would vomit at the mere sight of his bulging, pustule-ridden mass.    
In 260, he began putting into action a plan he had been slowly building to for millennia - having coerced Spellbreakers and cultists alike to feed his power. As his power grew in the Abyssal realms so too did his capability to weave tendrils of power into the world, and he wrought his evil touch to create the Boneplague, a horrific plague that was spread by his chosen cultists. The Spellbreakers had thought the situation under control and used the plague as an excuse to put-down the burgeoning Staldor clans in the South. However, things quickly got out of hand and the plague reached all the way to Klarta Dunn, just shy of the Neck. The number of plague-ridden corpses made in Baal'zurre's name fed his bloat even further, and whilst a number of adventurers had begun to try and make sense of the chaos afflicting South and Middle Eidos, they were too late - the cultists succeeded in their plan to summon Baal'zurre from the Abyssal Realms and to drag him into the Mortal Realm. His power was nascent, however, due to his fresh rebirth in mortal form, and the adventurers in question managed to defeat him and banish his soul back to the Abyssal. Doing so also cut off the power he was able to exert over the world, at least for the time being, and ended the Boneplague.    
The adventurers had thought Baal'zurre defeated, but in Markan Gowager 's waning days, he discovered a horrible truth - that Baal'zurre "lived", now residing within the upper levels of the Abyssal Realms, and sought once again to break through into the mortal realm. Having learned his lesson, he would wait longer before exerting his influence, and would emerge, this time, fully-powerful, bringing anarchy and disease in his wake to crumble mortal society beneath his sore-infested heel. Markan informed the heroes of Klarta Dunn of his fact, and they resolved to descend into the Abyssal Realms and destroy Baal'zurre's very spirit, once and for all. To do so is tantamount to suicide - but not doing so might well spell the end for the World, and all those within it.

Baal'zurre believes flesh is weak - a mere vessel for the destructive degradation of nature. His followers believe that in accepting the corruption of the flesh and the free-flowing of disease and illness, and becoming their own internal ecosystem of plague and carrion, that they can achieve immortality and true serenity. Baal'zurre believes all of nature is ruled over by the dominion of filth - and to transcend from a mere vessel to a carrier of natural destruction is the ultimate power one can possess.