<P> `` Invasion ! '' is the third annual Arrowverse crossover event , crossing over episodes of the Arrowverse television series The Flash , Arrow and Legends of Tomorrow on The CW , and is inspired by the 1989 comic miniseries Invasion ! . Events at the end of the Supergirl episode `` Medusa '' on November 28 , 2016 marked the beginning of the crossover , which officially began on November 29 with The Flash , continued on Arrow on November 30 , and concluded on Legends of Tomorrow on December 1 . Each of the latter three episodes were titled `` Invasion ! '' . `` Invasion ! '' sees Barry Allen recruit Kara Danvers / Supergirl to his Earth to help his team , Oliver Queen and his team , and the Legends to defeat the alien race known as the Dominators . </P>
<P> `` Invasion ! '' is the third annual Arrowverse crossover event , crossing over episodes of the Arrowverse television series The Flash , Arrow and Legends of Tomorrow on The CW , and is inspired by the 1989 comic miniseries Invasion ! . Events at the end of the Supergirl episode `` Medusa '' on November 28 , 2016 marked the beginning of the crossover , which officially began on November 29 with The Flash , continued on Arrow on November 30 , and concluded on Legends of Tomorrow on December 1 . Each of the latter three episodes were titled `` Invasion ! '' . `` Invasion ! '' sees Barry Allen recruit Kara Danvers / Supergirl to his Earth to help his team , Oliver Queen and his team , and the Legends to defeat the alien race known as the Dominators . </P>
what episode of legends of tomorrow is the crossover
what episode of legends of tomorrow is the crossover
Invasion !
Invasion !