after man of steel we should’ve got Batman V. Superman. few changes of course. First skip the Batman origin story, we all know it. Moving on, like the original film Batman is witnessing the destruction of a city as Superman fights Zod and this causes Batman to think of Superman as a threat and all that. So Batman comes out of retirement and is preparing for a showdown with Superman, only Batman should be the dark to Superman’s light. The film was very dark and gritty and so a balance would be to have the two opposites team up just how the joker and his crazy humor would be the opposite to lex Luthors stern attitude. But Lex Luther obtains his kryptonite sample which is the big huge Rock, whilethe Wayne foundation gets a much smaller sample of the rock, so Batman doesn’t steal the sample from lex like in the film. He has his own. Instead with the Batman coming out of retirement the joker returns as well, he thinks it’s time to bring more chaos. So just like the Batman and Superman animated film the joker and lex team up. So joker would steal the kryptonite, forcing lex into a partnership and after the showdown with Batman and Superman they realize that they shouldn’t be fighting each other and that they should be focusing on taking down their rivals together instead. we should get lex in his green armor suit like in the comics and joker planning to kill hundreds and stuff like that blah blah. And Wonder Woman showing up to aid them in this and they win in the end and that sets up the trinity of the justice league. The 3 main members. No Superman dying. And as an end credit scene the flash would appear from the future like the original film but to Batman, Wonder Woman, and Superman together to warn them of a coming threat.