Rules of Engagement:
1. Raito/Light and L are those respective characters at the time that they were at school together.
2. L has access to police backup (think backup that Commissioner Gordon may have)
3. Raito/Light has two Death Notes but not Risa’s ability to see the names.
4. Scarecrow and Joker both have henchmen around half of L’s force.
5. Scarecrow and Joker have access to Laughing Gas as well as the Nightmare Inducing Gas (you know, Scarecrow’s one, was never sure of the name).
6. The battle is terrorist, anti-terrorist in nature, set in London.
7. To win Joker AND Scarecrow must die or be arrested. OR L and Light must die.
8. No calling in backup from Gotham

, no case files of the Joker or Crane are available.