Celumbra, the Night's Dichotomy is a new craft legendary gear in 7.2. Requires lvl101 and can be traded in game. Because the map of the broken coast is very small, so there is the big chance for the fight between alliance and horde. This is a good use for this kind of craft legendary gear.

Celumbra, the Night's Dichotomy is made by the tailoring. The recipe can be bought and learned at the professional trainer. It needs tailoring 800. You need prepare 3 legendary items and some blood of Sargeras. Nethershard Essence can be exchanged by Nethershard or bought at an auction house with WoW Gold. But the Bolt of Shadowcloth and Bolt of Starweaveneed need to do some quests. You can get the quest from the Broken Shore.

In order to start the quest, you'll need to have the Nether Disruptor building active in the Broken Shore.

The quest giver is Eliezer Hammerbeard, located in Deliverance Point in Broken Shore.

Are you worried about the first legendary gear? Collect WOW gold to buy one at AH, this is also a good choice.