"Medusa" is the eighth episode of the second season from The CW television series "Supergirl", which aired on which date, the episode features a minor tie-in with the Arrowverse crossover event "Invasion!"?
Medusa (Supergirl): "Medusa" is the eighth episode of the second season from The CW television series "Supergirl", which aired on November 21, 2016. Invasion! (Arrowverse):  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!
November 21, 2016