How to Get Legendary Items in WoW Legion

There a few methods to obtain Legendary Items in World of Warcraft Legion and they are completely random and below are the known methods to get them:

1. All Dungeon Difficulties (The harder the difficulty, the higher the chances for it to drop) 
2. Emissary World Quest (Complete 4 World Quest) 
3. All Treasure Boxes (Including the ones in Dungeons) 
4. Battleground Boxes (Arena Skirmish Boxes do not count)

You can watch this video guide on how to obtain Legendary Items in WoW Legion 

All Legendary Items List

* You DO NOT need to be level 110 in order for a legendary to drop for you - however, you need to be level 110 in order to use it.