Barry (Grant Gustin) needed assistance from Earth 2 Dr. Wells (Tom Cavanagh) to defeat Gorilla Grodd in episode 7 of "The Flash" Season 2. The Flash is going to need a lot more help in episode 8. Luckily, reinforcements are on the way -- from Starling City! That's right, Oliver Queen (Stephen Amell) and co. will be joining the team at S.T.A.R. Labs in "Legends of Today" for the season's first "Flash"/"Arrow" crossover event

According to the synopsis for the new episode, Cisco (Carlos Valdes) and Kendra Saunders (Ciara Renee) head out on another date, but they are interrupted by a nasty bad guy named Vandal Savage (guest star Casper Crump). He has come for Kendra! Cisco and Kendra ask Barry for help, but the Flash realizes that Savage is a special kind of evil and calls in some backup. 

In the promo for the episode, that backup is revealed to be Oliver Queen and Team Arrow from Starling City. Oliver laments that the group only gets together to take down bad guys. 

"It's really great to see everyone. I wish it wasn't just the dark times that brought us together," Oliver tells everyone. 

He also has some unsettling info on Savage.

"He's an immortal," Oliver tells Barry.

Uh oh.

Meanwhile, the crossover event will also be helping to introduce the upcoming CW series "Legends of Tomorrow" and Kendra Saunders, a.k.a future "Legends of Tomorrow" star Hawkgirl. The synopsis reveals that a man with wings -- a.k.a Hawkman (guest star Falk Hentschel) -- shows up and flies off with Kendra and in the promo, Kendra has a lot to say to Hawkman about her new friends. 

"They are all willing to die to protect us," she says. "Don't you think that's a little insane?"

"I think that's what makes them all heroes," Hawkman replies. 

It looks like Kendra is going to become a hero herself in the episode, as a scene from the promo shows her sporting her Hawkgirl wings and flying off of a building, much to Cisco's amazment. 

Watch the promo for episode 8 below:

Will Barry and Oliver be able to take down Vandal Savage together? What will Cisco make of Hawkgirl's debut? Fans will have to wait to find out. "The Flash" airs Tuesdays at 8 p.m. EST on the CW.