The Troll Caves are a landmark added by Twilight Forest. These generate in and around the Highlands biome and is home to the Cave Trolls, unique to this area. Troll Caves are massive cave systems that sprawl beneath the Highlands biome, and some of these tunnels may be found in nearby biomes. These caves are decorated with Trollsteinn in the cave walls, and draping from the roofs are Trollvidr and Trollber. A point of interest is the Mushroom Vault, which houses multiple Obsidian Vaults and one Giant Obsidian Vault. The Giant Obsidian Vault can be mined through with the Giant Pickaxe to acquire the Lamp of Cinders.
Troll Caves can be found by finding Uberous Soil and digging down it.
Giant Obsidian Vault exterior
Inside of the Giant Obsidian Vault, with two double Chests inside