To be able to earn this pet your guild must complete every Challenge mode Gold.
We are currently selling the pet itself for 10k gold. How we do this is that we must invite you, or an alt on horde side and you must get to revered with Clarity and it will allow you to buy the pet. After you have hit revered and bought the pet you can either A, Leave or B, stick around but as an friend of the guild.
We will be taking the 10k from you before you invite and we can work things out with alliance members whom would like this via the neutral AH.
Contact us in-game or via this thread and we'll get back to you ASAP.
The Pet itself costs 275g From the vendor, also if you are exhalted with your current guild you will start out at honored with clarity when you join.