Green Riding Nether Ray

Grind Sha'tari Skyguard reputation to Exalted before visiting Grella. Start with the quest chain beginning with Threat from Above (given by Yuula, located near the Shattrath flightmaster) and continue through to Terokk's Downfall — skip all other quests. Using a class with an instant, spammable AoE ability such as a Mage, Discipline Priest, Guardian Druid, or Rogue speeds up the process significantly. Reputation bonus buffs from events like the Darkmoon Faire carousel or holiday buffs will also help.

Find Grella at 11.2, 39.2 in Terokkar Forest and purchase the Green Riding Nether Ray. At Exalted reputation with the Sha'tari Skyguard, the mount costs 160 Gold rather than the standard 200 Gold.