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The true name of the blood elves is Sin'Dorei, meaning "children of the blood" in Thalassian, they refer to themselves as blood elves in honor of their brave kin who were killed during the siege of Quel'Thalas by the Scourge. They used to be high elves but after that massacre they were changed forever.

They first appeared during the events of Warcraft III: The Frozen Throne, and later in the Burning Crusade expansion to World of Warcraft, they joined the Horde and the draenei joined the Alliance in order to balance the class system between the two warring factions.

Up until then Alliance players couldn't be shamans and Horde players couldn't be paladins, but Burning Crusade leveled the class system by allowing Blood Elves to become paladins and Draenei to become shamans.

Blood elves aren't servants of the light like the Alliance paladins, they instead bend the light to their will hence allowing them to use its specific abilities of Holy, Protection and Retribution.

Their racial abilities are what makes them different than other classes that can be paladins:

o Arcane Torrent will silence all enemies within an eight yard range for two second, as well as gain the blood elf six percent of his mana; in the case of a rogue or a Death Knight this will get you 15 energy or runic power.

o Arcane Affinity gives the blood elves a ten point bonus to their enchanting skill.

o Magic Resistance reduces the chance of being hit by magic attacks by two percent.