The Forbidden Spires (also known to be called Ancient Heights and Restless Range) is a Prime World biome filled with an Eastern-themed landscape. It exists in any Adventure Worlds of any difficulty, and has a themed world primarily featuring it in Uber-6, and can appear in either small patches or massive chunks of land. Cinnabar and Fiery Feathers can only be obtained here. Resources here are necessary for crafting the Ancient Phoenix mount as well as Stellar Rings.
Many different mobs will spawn in these lands. Enemies that roam this biome include ancient beings such as Jade Scarabs and occasionally creatures such as Spire Rams. Various Dragon Ogres (Sapphire, Jade, Amethyst, and Cinnabar) and Terracotta Giants has a chance to spawn rarely in this biome and will always have a boss modification and a large amount of health, making them formidable opponents.