Blizzard announced that the current season of MoP Challenge Modes will be ending with the pre-expansion patch. [source]
Thundering Serpent Hatchling In WoD
All MoP Challenge Mode achievements earned will become Feats of Strength. This includes the guild achievement that unlocks the Thundering Serpent Hatchling.
In addition to this change, updates from the WoD Beta indicate that the pet will not be available on the guild vendor in the expansion.
However, the Thundering Serpent Hatchling will not be going away any time soon. Those that purchased it prior to WoD will retain it in their collection, and those without it will still have a chance to collect it.
In WoD, you may see this little green dragon on the new Draenor BMAH every now and then. It's still unclear what the starting price of the Thundering Serpent Hatchling will be, or how often it will appear on the BMAH.
Collect Today!
If the prospect of AH bidding wars seems daunting, there's still plenty of time to join a guild that's unlocked the pet. You will need to earn revered with the guild first and foremost; the pet costs 300 gold.
For those still in need of the Thundering Serpent Hatchling, WarcraftPets has a Horde guild on US Madoran that is open to all collectors. Message any current member of Magical Menagerie for an invite. This is a family-friendly and fun guild, so everyone is welcome! Read the guild rules for more information.
If Horde doesn't tickle your fancy, we also have a list of other guilds (both Horde and Alliance) on US and EU servers that will accept collectors seeking the pet.
List of Thundering Serpent Hatchling guilds
Is it to0 late to do this now?
Like many others, I wish to thank the great community of people over at Magical Menagerie for allowing me access to the guild to get this pet. Here are some tips I learned along the way:
I went with a DK. Before you start questing in Havenshire, just after you get out of eBon hold logout and grab your main. If you have access to a 90 on another realm with access to a Renowned Guild Tabard you are set. Mail yourself one. You can mail cross-realm and cross-faction (toonname-realmname). There is a mailbox down in havenshire you can use to receive your mail. As soon as you complete the starting missions go to Outland and start those quests. It took me 10 hours over two days to gain the necessary rep. Now, Gold is the problem.... not really. Go back to your 90 and mail yourself a few more of those tabards. With a sell value of 62 gold each I only need three to buy the Hatchling.
A very big THANK YOU goes to Magical Menagerie. Thanks to them I was able to get the pet, as well as have enough gold left over to get the Reins of the Dark Phoenix and the Lil'Taragosa pet. The guild was awesome for allowing people to join to get the pet before it goes away :)
Just wanted to give a huge thank you to Pet Peeves; you folks were amazingly friendly and I've now got my thundering serpent hatchling. It was the only guild pet I was missing, and the lack was driving me nuts, so you have saved my sanity! ;)
-- Glabrielle/Kith
I just now got my hatchling, after joining up with Magical Menagerie a couple of days ago. Wanted to say extra thanks for any guild members that might see this, because you were all really friendly and welcoming, it was just a fantastic experience (I really can't say enough good things about it). I've joined Pet Peeves now, and intend to come back to hang out some more, to level my wee goblin priest and chat with people!
It's been a while since I got the Hatchling from Magical Menagerie, but even after 2 or so weeks, I'm still entirely grateful. It brightened up a pretty black time for me. Sick pets, relationship breakage, lots of doctorly visits... stuff like that all churned together into one ugly week. Then it was to be totally brightened up by a pet I had previously in the day marked as "Never getting... sigh". You guys are so generous, and I'm honored to have been and to be a member.
This is awesome and than you in advance! I'll be making my toon tonight!
On a side note do you have the guild MoP mounts as well?
HUGE thank you to the wonderful "a Guild" on Draenor (http://eu.battle.net/wow/en/guild/draenor/a_Guild/) for their help with getting this pet, managed to pay 270g for it with the guild bartering perk.
I just rolled a toon on Madoran. Thank you for being so friendly!
Got mine thru a friendly guild that offered to allow me to join. What a great thing to do for people. I guess I just have gotten used to people not extending themselves for others and this surprised me. Love my cute little pet.
I have mine but I just want to say you are awesome for offering to let anyone join to get theirs! <3
Another adding a huge thank you to MM for letting us all in. I had a blast and everyone was so friendly and helpful. You are all wonderful people! Much love from Belf Monk Claramy! :)
I definitely would like to extend a HUGE thanks to Magical Menagerie as well. I rolled a Horde Goblin Death Knight, and between BoA heirloom gear, a Guild Tabard, and the Goblin Racial for cheaper vendor prices, I had the pet within 3 calendar days of not-so-hardcore play.
The biggest hurdle was the gold it cost, BUT all of the Timeless Isle gear tokens are BoA and vendor for 5 gold each- farm the tokens on an alt and mail them to your new DK and you will win FAST!
Good luck!
Would like to thank all the people in Magical Menagerie for thier kindness and generosity in sharing this pet with all comers !
Thanks for the tip! The folks in Magical Menagerie are great (and right now, very busy moving pet collectors in and out with great patience and good humor!).
If I made a new toon on that server I'd have to make 300g somehow too right?
Huge thank you to everyone in MM for making this a pure joy and super easy to obtain!! I love you guys! <3
My daughters and I joined up yesterday evening and with newb quests were able to get to revered quickly enough to get the pet. What a wonderful opportunity you offered to us and we thank you very much! We're staying on on Warcraft Pets and gathering up Lil' Tarecgosa and the Dark Phoenix mount too. I am sure we'll come back to Madoran every time we want to talk pets too. Thanks again! So generous!
If the guild you join is at least level 24, the Thundering Serpent Hatchling will only cost 270g due to the Bartering perk. Every little bit helps if you're rolling a fresh character on new realm!