Kate Cassidy's Earth 2 Laurel Lance, the Black Siren, has been seen in two episodes of "Arrow" season 5. Now, the actress is set to appear in the season finale spin-off of "Legends of Tomorrow." It turns out that this is just a foretaste to the main course. TVLine reports that Cassidy has signed on "Arrow" season 6 and will be playing Black Siren.

A New Superhero On "Legends Of Tomorrow"

Before "Arrow" season 5 started Cassidy signed a deal that made her a regular on aCW superhero series. Thanks to some scheduling conflicts, Cassidy has appeared far less than other actors with comparable deals like John Barrowman and Wentworth Miller. However, fans can now expect to see more of Katie Cassidy on "Arrow."

Cassidy will first appear in the last two episodes of "Arrow" season 5 and then will become a series regular for the entire season 6.

"Arrow's" co-producer March Guggenheim said, "We couldn't be more excited to welcome Katie back to 'Arrow' as Black Siren, though as her presence on 'Arrow' and DC's 'Legends of Tomorrow' this season show, she never left the family," he added.

Why Black Siren Needed on "Arrow"?

It is uncertain on how Black Siren will be featured in season 6. Though Oliver assured he would try to redeem Earth-2 Laurel's memory, Black Siren had no interest in being "saved."

The fact that Dinah Drake has been enlisted to Team "Arrow" as the new Black Canary, seems to exclude Black Siren taking over her doppelganger's veil and maybe even join Team Arrow full-time. Two heroes with the same powers and backstories might not fit in Arrow's next season.

"Arrow" season 5 airs Wednesdays at 8/7c on The CW.