During the Event Period which is from May 18, 2022 (Wed) after maintenance to May 31, 2022 (Tue) before maintenance,  take the Quest: [Event] Making Waves with the Real Steed from NPC Lorenzo Murray The Stable Keeper in Velia, then interact with the Mythical Diné in front of NPC Lorenzo :

For more details, press ( O ) key to open Quests list >  New > [Event] Making Waves with the Real Steed 0/1

Then click on '' Move to '' to head to Lorenzo the Stable Keeper in Velia

Note: This quest can only be completed once per Family.  

The items obtained as a quest reward are materials used to awaken a Dream Horse or Mythical Horse, if you have any questions about that just let me know on my Discord : Dustan#0325

Enjoy you time !