Diablo 3 patch 2.6: Necromancer set: Grace of Inarius
This is a Necromancer set added in patch 2.6.0 featuring Bone Armor.
(2) Set:
Bone Armor damage is increased by 1000%.
(4) Set:
Bone Armor grants an additional 2% damage reduction per enemy hit.
(6) Set:
Bone Armor also activates a swirling tornado of bone, damaging nearby enemies for 750% weapon damage and increasing the damage they take from the Necromancer by 2750%.
This set is a melee set and currently the most powerful Necromancer set. The 2 pieces bonus does decent damage. Therefore, use Bone Armor whenever you can. 4 pieces bonus increases 10 stacks Bone Armor damage reduction from 30% normally to 50%. (With Wisdom of Kalan amulet you can have 15 stacks Bone Armor, further increase the damage reduction to 75%.)
6 pieces bonus greatly increases damage to mobs within the tornado around you. Therefore, you need to stay close to the mobs to benefit from the set bonus. It does not limit which skills you use for damage, so you can have different builds with this set.