Related Clues:
- Sources of frustration
- Holmes and Moriarty, e.g
- The Steelers, to the Ravens
- Formidable foes
- The Ravens, to the Steelers
- Unbeatable foes
- Tough rivals
- Luthor and Zod, to Superman
- Causes of destruction
- Downfalls
- Agents of undoing
- Fearsome foes
- Tough opponents
- Joker and Riddler, to Batman
- Sources of ruin