I have been thinking about this for a while now and decided to go ahead and post it up.
How cool would it be to see the JLA go at it with the JSA? Well I am a pretty decent artist who is still learning and getting better at drawing and would love to draw it out the best I could to bring the idea to life but a writer is definitely needed.
As far as the story goes I thought of this...
The Justice League is busy fighting Braniac on his ship. They are able to take him out until they are unknowingly infected with these "nanites" that are on Braniac's ship. However the JLA still end up saving the day and stopping Braniac.
Meanwhile the JSA are hanging out at their base until a very weak Alan Scott from the future enters their head quarters from a portal made through him warping through time. He warns them that within the next 2 years the Justice League goes mad and begin to wreak havoc among the entire world and even kills the Teen Titans and The JSA with Alan being the only survivor. (The reason why the Justice League begin there destruction on the world in the next 2 years is because of the nanites they were infected with from braniac's ship.)
The Alan from the future tells them that the Justice League must be taken out now while there is still time left. With the JSA now knowledgable of this information they decide to take out the Justice League in order to save the world and from then on....its all out WAR!
While at the same time the JLA try to figure out a cure to stop themselves from destroying the world as well :)
If interested contact me or let me know!