The Demon Soul, formerly known as the Dragon Soul, was an artifact created shortly before the War of the Ancients. Though it appeared to be a featureless golden disk, it was in fact a talisman of immense power created by the Aspect of the black dragonflight, Neltharion the Earth Warder... later known in history as the Black Scourge, .
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After you cast 3 spells in a turn, summon a 5/5 .
- See this subject on WoWWiki: Demon Soul