The first five episodes of The Flash’s Season 8 have been revealed to be an Arrowverse cross-over that will also feature Javicia Leslie‘s Ryan Wilder/Batwoman, Katherine McNamara‘s Mia Queen/Green Arrow, Brandon Routh‘s Ray Palmer/The Atom, Cress Williams‘ Jefferson Pierce/Black Lightning, Chyler Leigh‘s Alex Danvers/Sentinel, and Osiric Chou‘s Ryan Choi.
A powerful alien threat arrives on Earth under mysterious circumstances and Barry (Grant Gustin), Iris (Candice Patton), and the rest of Team Flash are pushed to their limits in a desperate battle to save the world. But with time running out, and the fate of humanity at stake, Flash and his companions will also need to enlist the help of some old friends if the forces of good are to prevail.
It has also been reported that Tom Cavanagh‘s Reverse-Flash and Neal McDonough‘s Damian Darhk will also make appearances.
The Flash showrunner Eric Wallace added:
“Simply put, these are going to be some of the most emotional Flash episodes ever. Plus, there are some truly epic moments and huge surprises that await our fans. And we’re doing them on a scale that’s bigger and bolder than our traditional Flash episodes. So yes, ‘Armageddon’ is a lot more than just another graphic novel storyline. It’s going to be a true event for Flash and Arrowverse fans, old and new. Honestly, I can’t wait for audiences to see what we’ve got planned.”
From the title my guess would be a link to Armageddon 2001 but the story does not fit this at all from what they have revealed so far. Either way I think Ray Palmer is either the future villain or dies saving the universe in this one.