Zaven the Alchemist
Zaven is a lottery-spawned NPC Merchant that opens the door to the Mysterious Cave in Dahlgar Oasis for the liquid rainbow. When you stumble upon him, he'll be attacked by 3 ghost. Once you save him, he'll open the doors to Mysterious Cave.
He can be spawned at 1 of 2 locations; From the way point Path to Oasis, just hug the right wall until you end up in a dip or if you take the Dahlgar Oasis Way point, he'll be slightly South (more east) of the way point. Both location looks exactly the same.
If he's not at any location, he wasn't spawned and you will need to recreate the game again.