To Unlock Ultimate Gear you must have an ilvl of 490 or more (full Mythic+10)
a new gossip option appear on Wrathion to start the questchain.
1- Learn more about new threats Warsong is facing and turn in the quest to Ysera.
2- Collect Tormented Soul from illidan (10% chance).
3- Collect the Legion's Greater Axe from Zuma (5% chance).
4- Collect the Greater Felhide at the end of Legion Invasion event (7% chance).
5- Bring 30 Honnor and Arena Marks.
6- Bring 30 Gul'dan FelFire and Antimatter.
7- Bring 30 Legendary Courages.
8 - Bring 50 Daily Tokens and 500 Enchanted Debris
9- Bring 1000 FelBlood, 100 Demon's Marks et 50 Pure Gold Essences.
10- Bring 20 Heroism Emblem and 100 Power Fragments.
11- Bring 20 Heroism Emblem, 20 Mascot Tokens and 20 Magic Leather.
12- Finally Speak to Wrathion to accept and validate the quest.
Congratulations! you now have the Ultimate Stone and you can access the Naxxramas Raid to Improve your equipment.