Sentence:  We believe a <WSD>corruption</WSD> has started, we have feared this day for many years; ever since we got reports that a dark cult containing a small amount of members had been praying to the underworld god Volkin, and that they were never caught. 
Meaning of the word marked with <WSD> tags:  (en) Something originally good or pure that has turned evil or impure; a perversion.