Blood War The Blood War is an ancient conflict that once raged between the Fiends of the Lower Planes . The Tanar ' ri are the demonic forces of the Abyss , an evil plane of chaos . Representing the equally evil but lawful realm of Baator are the Baatezu , the dominant caste of devilkin . Neutral evil Yugoloths played both sides against the other . The Blood War had raged on since the Age Before Ages , a dark time when the Prime Material Plane had not fully developed . The conflict was massive , spanning entire planes of reality , and hosting an almost infinite number of fiends . Motivations . The cause of the Blood War is unknown , but most believe it to be a remnant of the great war of Law against Chaos waged by the Wind Dukes of Aaqa against the forces of the Queen of Chaos . The yugoloths liked to entertain the notion that the War was their own personal experiment into the nature of evil , one which they created and would ultimately end on their own terms . Of course the other fiends had their own notions about the war , colored by their particular alignments and racial propaganda . Some demons and devils seemed to believe that their respective races could actually gain control over the other . However , the most powerful archdukes of Hell and the most cunning princes of the Abyss paid the Blood War little concern , and if entities as ancient and formidable as they seem unconcerned , then the cause would most likely be a fruitless one . Many lesser fiends actually embraced the War , for it staved away the cosmic boredom of being ageless . A few races survived on the carnage the Blood War produces ; the armanites , centaur - like tanar ' ri , must constantly battle with other creatures , for otherwise they will turn on one another ; the molydei are another race of demons who prowl the Abyss , searching for deserters or rogue demons , whom they press - gang into fighting . Certain creatures were bred by other fiends exclusively for the Blood War , including the Nessian warhound s and the milvorn . Even the yugoloths were given purpose by the Blood War ; forever shifting from one side to the other , they as a race gained much of their wealth and power from the spoils of war and the high price of their services , though some ( including the yugoloths themselves ) believed this to be simply a facade over older and darker motivations . The " " dictates that the Blood War was a simple offshoot of the primordial wars between law and chaos ( it is unknown as to whether the lawful good - aligned archons and chaotic good aligned eladrin s participated in the conflict ) . The demons and devils ( in keeping with their sadistic and violent natures ) simply would not cease their fight , even after the rest of the multiverse had grown more tolerant . Outcome . Despite millennia after millennia of constant strife , no side had been able to gain even a definitive , permanent advantage over the other . Despite their vast differences , the tanar ' ri and the baatezu were surprisingly balanced combatants . The chaotic denizens of the Abyss , while far more numerous than the devils , are , true to their alignment , constantly warring amongst themselves . They could contest the might of the Nine Hells only through sheer individual power , and their seemingly limitless , if unorganized and uncoordinated supply of warriors . The baatezu , on the other hand , deployed smaller numbers onto the field , but their warriors are regimented , well - trained and well - disciplined , all the while making incredible use of their generals ' ruthless strategies . This violent balance could have kept the Blood War fueled for an indefinite period of time . One thing , however , is certain : had one side been able to eliminate all opposition , and thus gain control over the entirety of the Lower Planes , the multiverse as a whole would have been in great danger . With no enemies left in the Lower Planes , the fiendish rulers could then have turned their attentions towards other worlds and planes , and it is likely that no force could hope to stop them . Even the celestial beings of the Upper Planes , formidable as they are , could face destruction at the hands of the tanar ' ri or the baatezu , weighed down by their alignments demand by the needs of good and justice — the fiends , having no such compunctions or scruples , could easily have used the celestials ' morality against them . In the past , agents of the heavenly races had even planted powerful weapons or artifacts among the ranks of the demons or the devils . This appears to be a reliable indicator that even the beings of the Upper Planes did not want the war to end . There is a prophecy that says that the Blood War would end when the Crawling City , a city on the plane of Gehenna that is home to millions of Yugoloths , directly enters the Blood War . This proved untrue , as once Asmodeus regained his divinity by absorbing the divine power of Azuth he ended the blood war by pushing the Abyss to the bottom of the Elemental Chaos . Thus the seemingly eternal Blood War finally came to an end at the hands of the deified Archdevil Asmodeous ; with the devils thus victorious in a manner of speaking . A few things are certain , Once again the river Styx flowed through the Nine Hells and the Abyss , The Tanar ' ri still have their eternal hatred of the Baatezu , The Tanar ' ri will reach out and strike at their hated eternal enemy and the Tanar ' ri really have nothing stopping them from engaging in the Blood War . High ranking officers . The Dark Eight are a coven of pit fiend generals who reside on the Ninth Layer of Hell , Nessus . They plotted and strategized the movements of Hell ' s armies . Bel , Lord of the First Layer , was once a mighty leader on the battlefields of the War , and used his influence with the Dark Eight to retain control of Avernus . Baltazo , a grotesque minor Demon lord , was also a mighty general in the Blood War , but has since retired to the Plain of Infinite Portals . Interestingly , the greatest powers of the Nine Hells and the Abyss did not take an active role in the Blood War . The sole exception from Baator was Bel , Lord of Avernus . The mighty pit fiend has strong ties to the Dark Eight , the pit fiend generals who oversaw all of Hell ' s involvement in the War ; this relationship kept the relatively weak Bel safe from the other archdukes . The mightiest demon princes , such as Orcus , Graz ' zt , and Demogorgon , constantly war with each other within the Abyss , and had little concern for the Nine Hells . Asmodeus himself built a mighty force of devils within his fortress of Malsheem in wait of a cataclysmic battle he claimed would dwarf the Blood War .