
Originally Posted by
Vaedan
What I recall these very few blood mage NPCs seen in action use mixture of both mage and warlock fire spells plus spells not available to any playable class.
Sure, we've seen them use arcane spells and even frost spells which points out to mage class, but only various drain spells (life drain, mana drain, blood drain) and banish spells, so that leads to warlock. On that matter, I feel that blood mage is supposed to be a combination of mage and warlock archetypes.
Also don't forget that blood mage siblings (plus a gnome blood mage Kasim Sharim) in Blasted Lands who display extraordinery knowledge of demonic magic.
Also note that blood magic was something not defined in the game until WotLK and introduction of DK blood spec. Until that time, no blood mage used "Real" blood magic as we've seen later in WoD and BfA. Before that, blood mages were known for their usage of fire magic, which is something that leaves the impression of demonic magic and could be mistaken by such magic. Both warlock and mage spells fill the bill here, so I'm not surprised anyone is connecting that fantasy to warlocks too. Soul shards floating around your character made that fantasy even more approachable.