Minecraft wiki entry for Best_biomes_to_play, associated text: Soul sand valleys are the #3 most dangerous biome, because of the soul sand everywhere can slow you down and cause the skeletons and ghasts that generate in this biome to hit you more accurately. Any fire in this biome ends up as soul fire, which does 2 times as much damage than normal fire. If you don't bring good armor then this biome can cause death pretty quickly. There are also nether fossils in this biome, so if you find one you can grind the bone blocks into bone meal for growing your crops quicker.