The term 'Cause of Ruination' can be summarized by two crossword solutions: DOWNFALL (8 letters) and BANE (4 letters). DOWNFALL is a noun that refers to a sudden or catastrophic decline, collapse, or destruction. It is often used in the context of a nation, organization, or individual's decline or destruction. BANE is a noun that refers to something that causes ruin, destruction, or death. It is often used to describe an evil force or person that brings about destruction. Both words are used to describe a cause of ruination, which is the act of bringing about ruin or destruction.