The Three-Headed Dragon is a LEGENDARY pet that is available from the Magma Egg found in the Volcano area of the Spawn World.
The latest Pet Simulator X value list for Three-Headed Dragon can be found below:
💎 7,000 (7k)
💎 20,000 (20k)
💎 66,000 (66k)
💎 280,000 (280k)