Stardust
Quest reward from A Celestial Invitation. In the end, we are all wrought from stardust. Magic type. “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars.
Stardust is a battle pet rewarded from the quest A Celestial Invitation, which becomes available after completing the Raiding with Leashes IV: Wrath of the Lick King achievement and defeating Algalon the Observer in a pet battle.
Guide awaiting review
Complete Raiding With Leashes IV
Collect all 16 required pets to complete the Raiding with Leashes IV: Wrath of the Lick King achievement. Once completed, you will receive 
Celestial Invitation in your in-game mail on the character that obtained the 16th pet, offering the quest A Celestial Invitation.
Find Algalon the Observer
Head to Algalon the Observer at 41.5, 24.2, found at the base of the stairs outside the entrance to Ulduar. He has left the raid to challenge you to a pet battle as part of the A Celestial Invitation quest.
Defeat Algalon's Legendary Pets
Algalon fields three legendary pets: Comet (dragonkin), Cosmos (magic), and Constellatius (magic). A reliable strategy is to lead with a Macabre Marionette against Comet using Siphon Life, then bring in an Emerald Proto-Whelp for Cosmos, and use a third pet to absorb damage. Waiting 15 turns will cause the final pet to defeat itself.
Complete the Quest
After defeating Algalon the Observer, complete A Celestial Invitation to receive Stardust. The pet shares the same appearance as Algalon's own Cosmos and has a speed-focused breed with 309 speed, 1441 HP, and 268 power at level 25.
Tips
Stardust has a speed-focused breed, making it a strong candidate for pet battle teams that rely on going first.
