After you complete this week’s Story quest, you unlock a vendor with new transmogs!
Hearthstone
You can unlock a new Hearthstone!
Path of the Naaru – 90 Lightweave Cloth, 90 Empyrium, 900 Veiled Argunite
New Weapon Transmogs
Once you complete the questline, you unlock one last quest that allows you to buy these transmogs.