Reins of the Thundering Onyx Cloud Serpent is looted from Huolon, a rare elite cloud serpent flying above the Blazing Way on Timeless Isle. Its spawn time is the same as many of the regular rares on the island. It also has a chance to be listed on the Black Market Auction House.
Here you can buy Thundering Onyx Cloud Serpent for EU or US Servers.
You'll get guide for getting Thundering Onyx Cloud Serpent
You'll be able to get Thundering Onyx Cloud Serpent
Thundering Onyx Cloud Serpent mount
Additional budget for Character transfer or Character boost to max level. BMAH Services in Shadowlands now requirement to have a max level character on server, so Trial character will not work.
Free time on evening, if you choose selfplay option