The Flash Season 5 Finale Preview Released

All season on The Flash, the heroes have been working towards defeating a dangerous villain whose entire focus is the killing of metahumans. First, they were fighting Cicada, a man named Orlin Dwyer, only for that Cicada to ultimately end up dead at the hands of Cicada II -- a future version of Dwyer's niece, Grace. Now, with the finale in sight, Team Flash has discovered that things don't quite add up with Cicada II and it's been revealed that there's an even bigger bad behind it all: none other than Reverse Flash. Now, in a new promo, it appears that Team Flash will be dealing with both its oldest enemy and its newest in a tense season finale.

The CW has released a promo for "Legacy", the season five finale of The Flash. In recent episodes, it was revealed that Nora West-Allen -- Barry and Iris' daughter from the future -- was working with Reverse Flash/Eobard Thawne, though it appeared that he had been helping her at her request. However, tonight it was revealed that Thawne has been manipulating the situation the whole time, deliberately positioning things to where Team Flash would attempt to "destroy" Cicada's dagger. It appears that by doing so, Thawne will end up with the dagger in the future, allowing for the villain who has been imprisoned in the future, to end up in The Flash's present, forcing Barry to face his worst enemy all over again -- as well as the possible death of his daughter at the hands of Cicada II.

This, along with some of the other changes to the timeline that have been made as a result of Nora's arrival in the present, will apparently make "Crisis on Infinite Earths" happen in 2019 instead of 2024. If that's the case, it could mean major changes to the Arrowverse overall, including the popular fan theory that Arrow's Oliver Queen will ultimately sacrifice himself to save Barry once "Crisis" arrives this fall, something that was somewhat teased in this season's "Elseworlds" crossover when Oliver spoke with the Monitor in an attempt to prevent both The Flash and Supergirl dying to save the world in that struggle as well. Whatever the case, "Legacy" could be a huge hint towards what's coming in "Crisis".

You can check out the official synopsis for "Legacy" below.

BARRY FACES OFF WITH REVERSE FLASH – Barry (Grant Gustin) faces off with his oldest, and most formidable nemesis, Reverse Flash (Tom Cavanagh). Gregory Smith directed the episode with story by Lauren Certo and teleplay by Todd Helbing & Eric Wallace.

The Flash airs on Tuesday nights at 8 p.m. ET/PT on The CW. "Legacy" will debut on May 14.