The first rule is... There are no rules.
A new TV spot for the season finales of Arrow and The Flash has hit the web, and it finds the heroes joining Black Canary, Arsenal, and a host of villains in a satirical superhero fight club. Check it out right here to see who comes out on top.
Also hitting the web a few days ago, this Flash clip for the episode "All-Star Team-Up" shows Ray Palmer introducing his new codename, and enlisting Harrison Wells for help with his suit.