Arrow and Legends of Tomorrow’s executive producer Marc Guggenheim recently revealed some telling details about upcoming crossover elements in the Arrowverse, specifically the appearance of several characters on Legends, including Black Flash.

Guggenheim says, “We, just yesterday, made an offer to an actor to reprise their role from one of the other shows in the season finale of Legends … Oh, and in the penultimate episode we’re gonna have — I can’t be specific about this, but it’s one of the most fun things I think we’ve ever done on the show — a character from one of the other shows on Legends in a way that you’ve never seen before, you may never see again, but will, I think, just send fans into squeals of joy.”

It’s unclear which characters he’s talking about, but Robbie Amell’s Ronnie Raymond (the original other half of Firestorm) is slated for a return to The Flash later this season as is Rick Cosnett’s Eddie Thawne, so either one is a possibility, with the former being more likely for a program like Legends.

Guggenheim also straight up confirms, “We’re going to be seeing the Black Flash on Legends,” so there’s a chance that it’s Teddy Sears’s Jay Garrick/Zoom popping up in the finale. You’ll remember he was consumed by time wraiths in the Season 2 finale of The Flash. Whoever it is that will make the move to Legends, we’re looking forward to the “squeals of joy.”

Next week’s episode of Legends will also feature another appearance from Lily Stein, Professor Martin Stein’s “time aberration” of a daughter, a character that originally popped up in The Flash portion of the Invasion crossover event.

Guggenheim also said that next week’s episode of Arrow has “the fastest crossover with Flash we’ve ever had,” so look forward to that as well.

Legends of Tomorrow airs Tuesdays at 9.

Photos via Comicbook.com