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This will boost your survivability and allow you to last longer and tank more damage. Get three if you can afford to. This build relies heavily on your damage output, as such, rubies will be a good asset. A little bit more extra damage can't hurt since you already have the resistance from the Immortal King set, assuming you got that set. These can be a bit pricey. If you can't afford it, get a +% to health instead. Any of these would be beneficial to the Barbarian. These are the two main armor stats that you should be focused on. The weapons must have sockets for Emeralds for additional critical damage; it should also have either +Attack Speed or +Critical Damage.
Get the Immortal King set. Socket Good Rubies into your chest piece. Get +Critical Damage and +Attack Speed on your gloves and bracers. Get either a +Critical Chance or a +Critical Damage on your amulet. Get rings that have +Critical Chance, +Critical Damage, or +Attack Speed. Get items with either Vitality or Strength. Get an on-hand and off-hand weapons.