VS
After messing around in another reality, Mr. Mxyzptlk offers to send the Justice League back to earth... he just doesn't specify which Earth.
The Justice find themselves teleported into a city that looks like a disaster hit it. (It was actually the Wrecking Crew, but their long gone now.)
About the same time, the Avengers receive a distress call saying some unknown superteam is tearing up the City.
Each team suspects the other group is the villains. Neither has any clue who the other team is.
Bloodlust is OFF. Characters will remain entirely in character, which includes the fact that characters aren't going to be speedblitzing each other left and right.
The Justice League Line-up consists of
Superman
Batman
Hawkgirl
Martian Manhunter
Green Lantern
Flash
Wonder Woman
The Avengers are ...
Captain America
Ironman
Thor
Hulk
Black Panther
Wasp
Antman/Giantman
Hawkeye
Ms. Marvel (even if she isn't in the picture)
The Team faces off and after a bit of "Stand down!" "No, YOU stand down!" Hawkeye fires the first arrow... and the fight is ON!