Felblood Felblood ( or fel blood ) is a term that refers to the blood of demon s , evil immortals who feed upon life and magic , whose blood is infused with fel . The blood of most demons holds a substantial amount of power and there is no telling what the inexperienced might do with a draught of demon ' s blood . Blood Curse . Gul ' dan had persuaded the highest - ranking orcs of Draenor to drink demonic blood . It was this stain that had hounded them for so long . Even those who had not partaken found themselves developing an unquenchable thirst for slaughter , their skin turning green with the taint . The demon blood most of them had imbibed back on Draenor had increased their natural bloodlust a hundredfold . The orcs , their systems permeated with demonic blood , burned with a lust for killing that would not be sated even if they slew every last draenei on Draenor , would never be sated until death stiffened their corpses . Lethargy of the Orcs . Cut off from their sustenance , the orcs slipped into a state of lethargy . Antonidas learned that the orcs had been under the crippling incluence of demonic power ( or warlock magics ) for generations . He speculated that the orcs had been corrupted by demonic powers even before their first invasion of Azeroth . Clearly , demons had spiked the orcs ' blood , which in turned granted the brutes unnaturally heightened strength , endurance and aggression . Antonidas theorized that the orcs ' communal lethargy was not actually a diseases , but a long - term racial withdrawal from the volatile Warlocks magics that had made them fearsome , blood - lusted warrior . Though the symptoms were clear , Antonidas was unable to find a cure for the orcs ' present condition . Many of his fellow mages , as well as a few notable Alliance leaders , argued that finding a cure for the orcs would be an imprudent venture . Left to ponder the orcs ' mysterious condition , Antonidas ' conclusion was that the orcs ' only cure would have to be a spiritual one . Redemption . It had been Grom who had first drunk the blood of the demon Mannoroth - blood that had tainted him and all others orcs who had drunk it . But in the end , Grom had had his revenge . Though he had been the first to drink , and thus the first to fall to demonic bloodlust and madness , he had been the one to end that madness and bloodlust . He had slain Mannoroth . And with that gesture , the orcs had begun to reclaim their own great hearts , wills , and spirits . Slime . Slimes will literally drain the life from its victims , as heat is what it uses as food . One of Laris Geardawdle ' s biggest theories is the idea that oozes and slimes are tied to the creation of this planet , almost like they ' re a secretion of it . In Felwood slimes are found all around pools of water blessed by the touch of Fel . The Scourge decimated the area with attacks of Infernals and other demonic magics - - the slimes supposedly crept up through the earth during these attacks . Fel magic drains life , like slimes , and according to Loreology , one of Blizzard ' s lore historians , fel is entropic as in it destroys life . Felblood would be entropic like the ooze tainted by the Old God Yogg - Saron and might have a connection to him . RPG . The ultimate manifestation of the demonic arcane on Azeroth is fel ( aka fel energy or fel magic ) . This energy , which most commonly manifests itself as ghastly , green - yellow flame , is arcane magic at its most corrupt , for it employs the blood of demons . Fel magic is pure arcane ; it resides in the blood of demons . This blood has magical properties ; it addicts arcane magic users and can be used to create evil weapons . When a weapon is forged in demon blood , it becomes a fel weapon . It glows with a foul , yellow - green fire and deals extra damage to good - aligned opponents . Some arcanists can cast fel spells , perhaps after drinking demon blood . Felblood is highly addictive as well as corruptive . Demon s sometimes tempt spellcasters by offering small amounts of their blood in exchange for services . Anyone who drinks felblood has a chance of becoming dependent on felblood , and unless the person continues to drink it daily , he will suffer withdrawal symptoms . He has a chance of breaking the addiction seven days after first drinking the felblood .