Batman has a very specific code that is on every Leaguer‘s communicator and that he warns them to "Never tap into it unless I’m indisposed and the world is two seconds away from ending."

Fast forward a few years and Batman is knocked out cold and the world is two seconds away from ending when the JL remembers Batman‘s very important "do not tap unless absoloutely necessary"-button. So obviously the JL taps it, expecting some sort of god or something.

Instead a woman picks up. She‘s simultaneously yelling commands, tapping aggressively on a keyboard and calmly telling them that she‘s Oracle, that she’s already linked every person on the battlefield’s comms to the Bat-Family comms and that she‘s sending reinforcements as they‘re speaking.

Then, while the JL is still in shock, Red Hood, the f*/cking drug lord, lands beside them and starts shooting up enemies. Nightwing is further back, backfliping. Red Robin is doing his stuff. A mysterious, black cowled girl pops up beside them and starts gently ordering them to specific parts of the battlefield. Hal gets so spooked he screams while a fully purple girl is beating up enemies next to them. A guy in neon yellow is punching enemies to the ground and some random ten year old is screaming as he incapacitates enemies thrices his size.

Hal almost jumps onto Superman‘s arms when another figure lands right next to him, seemingly appearing out of thin air.