The Enchanted Forest is a biome added by the Twilight Forest mod. This biome is moderately rare, and is the only place to find Rainbow Oaks, Fiddleheads, and the Quest Grove with the Quest Ram. This biome's natural blocks, such as leaves, plants, and grass, cycle between colors based on world coordintes. You can also find Canopy Trees, Oak Trees, and Birch Trees in this biome.
The foliage color variation forms concentric rings around the point at which the Quest Grove could spawn (if other conditions are satisfied).