The Comics: DC on The CW is well-known for managing time traveling stories very well. One of the comics’ major crossover events by Dan Jurgens was that of 1994’s Zero Hour, where the DC super heroes deal with alternate timelines and possible futures. In this storyline the time stream is completely muddled because heroes-turned-villains are trying to rewrite history, starting in the far future and working their way back to the past. During all this, the DC Universe heroes encounter abnormalities and alternate versions of each other facing the universe’s progressive destruction. The whole ordeal has Time Trapper, the entity that watches over time, killed by a vengeful heroe (Spoiler: Green Lantern/Hal Jordan) and then resurrected to witness a new Big Bang that reshapes the universe back into what the DC writers wanted as a retcon.
The Crossover: A lot of elements of this particular comic book event have already been seen in the Arrowverse. If the Legends of Tomorrow are front and center, the story writes itself; especially since all these characters can be introduced in their show first. The story in the comics begins with characters and places vanishing from existence, so imagine the Legends on the Waverider having to go pick up remaining heroes from all over the Multiverse to try and figure out who made an even greater mess of the timeline. Instead of characters like Green Lantern going evil, how great would it be to see a future, senile Roy Harper trying to shape the timeline because his life went to shambles after he faked his own death? This could be Barry Allen’s redemption for Flashpoint when helping the Time Trapper. Also, in the comics, Hawkman merges with various version of himself. Maybe Falk Hentschel could come back to reprise all the versions of himself from history.