Hellgrowth

Ignium-Wasche, more commonly known as Hellgrowth is a result of the Nether spilling forth into the overworld either through divine intervention, carelessness with portals or intentionally by people.

Examples
Currently, the ruins of Asahiri and Tarnwick are completly engulfed in Hellgrowth.



Meta of Hellgrowth
Normally Hellgrowth is created through WorldEdit or the naturally generating Ruined Portal structure. But, it makes storytelling more interesting if we remove this detail.