World War Alien

*Set a week after "Duet" the musical crossover between Flash and Supergirl
A threat is looming over the multiverse, and it is threatening earth 1 and earth 38.
The heroes will soon realize that they have to team up and work together again to prevent the destruction that is coming to the multiverse. Is everything as simple as it seems though?
Along the way, drama arises and bonds are broken. The heroes learn that there is a lot more to the issue than meets the eye and old faces arrive. Will they be able to overcome their differences and work together? Will they be able to stand as one? Or will they crumble against the pressure and fail?