Universes collide as the Source Wall has been breached. The Marvel and DC universes seem to have merged. This allows a team-up of Dark Phoenix and Darkseid to threaten everything. Can the Uncanny X-Men and the New Teen Titans overcome their differences, stop fighting between each other, and team-up to save both Universes?
Note: This story takes place when Beast Boy went by "Changeling," Nightwing went by "Robin," Donna Troy went by "Wonder Girl," and Flash (Wally West) went by "Kid Flash."