Heroes Join Forces

"Heroes Join Forces" is the second annual Arrowverse crossover event, featuring episodes of the television series The Flash and Arrow on The CW. The episodes feature characters from DC's Legends of Tomorrow, which was being developed as a spin-off. The crossover sees Barry Allen / Flash and Oliver Queen / Arrow team up to take on Vandal Savage, who is looking for Kendra Saunders and Carter Hall, the reincarnations of Hawkgirl and Hawkman.