Level 70 Fury Warrior Solo: Uu'nat, Harbinger of the Void (Normal difficulty) 

Pretty easy fight, though you need to be considered a DPS spec/class to have access to the Tempest Caller relic in case any Undying Guardians are summoned (they can't be killed otherwise and they prevent the boss from taking damage while they're alive).
ilvl 398, Berserker Stance