Bloodmages are practitioners of blood magic. They were prominent in the Valyrian Freehold, and are welcome in Asshai, were they can practice their arts and rituals with impunity. They are said to work their terrible sorceries at night.
Septon Barth, in his Dragons, Wyrms, and Wyverns: Their Unnatural History, speculated that the bloodmages of Valyria employed wyvern stock to create dragons.
In flesh pits of the city of Gogossos, bloodmages mated beast to slave-women to bring forth twisted half-human children.
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