DF release means some old raid mounts that were guaranteed drop are now converted to rare drops.

• Fractal Cypher of the Zereth Overseer from The Jailer, Sepulcher of the First Ones (Mythic)
• Vengeance's Reins from Lady Sylvanas Windrunner, Sanctum of Domination (Mythic)

(don't forget to set wasGuaranteed = true)