“After learning the Dominators’ plan for the world, the Legends must work together with The Flash (guest star Grant Gustin), Supergirl (guest star Melissa Benoist) and Green Arrow (guest star Stephen Amell) to kill them once and for all.
“Oliver and the recruits take on a new threat with help from The Flash (guest star Grant Gustin) and Supergirl (guest star Melissa Benoist).”
The Flash episode is described as follows: “When aliens called the Dominators attack Central City, Barry (Grant Gustin) speeds over to Star City to ask the Green Arrow (guest star Stephen Amell) for help in stopping them.
Last night’s episode of Supergirl got the ball rolling on The CW‘s “Invasion!” crossover and now the promo for The Flash episode that continues the four-night event has debuted online!