Title pretty long. When boss will cast Chaotic Shadows (debuff on the end of which spheres will be thrown at all directions from a player that wear that debuff), it will anonce it with alarm sound, type in chat which player got debuff and mark them (triangle, skull, square and with other marks). It must made your way to dodge spheres, avoid players with marks and split on the arena easier, especially with random players in your party.
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It will work only if you have English and Russian version of WoW, other languages does not supported.