Tainted Lands (Thaumcraft 4)

Tainted Lands is a biome added by Thaumcraft 4. It is an infectious biome that spreads Taint that corrupts adjoining land into more Tainted Lands; for example, tree log blocks eventually become Crusted Taint and Dirt becomes Tainted Soil. Its progress is halted by bodies of water, Pure Aura Nodes, and Ethereal Blooms. They originate from a Tainted Aura Node; moving this Node elsewhere will cause Taint to spread from it. Because it is abundant in blocks and other resources which have been tainted, this biome is one of the best (if not only) places to procure essentia.

Players exploring the Tainted Lands should exercise caution as they will be afflicted with Taint Poison—a status effect similar to Wither—infrequently if they spend too much time in the biome.