The CW's four-night crossover event between its DC Comics-based shows continued tonight on "Arrow," in a special 100th episode celebration of the series that started the Arrowverse. The crossover will conclude tomorrow night on "DC's Legends of Tomorrow," and a new promo previewing the final has made its way online.

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In this new clip, the team faces the Dominators in both the past and the present. Barry Allen is also being targeted by the Dominators, and is asked to sacrifice himself for the safety of the planet.

ALL FOR ONE AND ONE FOR ALL IN THIS CROSSOVER OF SUPERHEROS — 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. Meanwhile, Stein (Victor Garber) figures out, with the help of others, how the team can terminate the Dominators, but is distracted by the aberration he realizes he created in 1987. Brandon Routh, Franz Drameh, Dominic Purcell, Maisie Richardson-Sellers, Nick Zano and Caity Lotz also star. Gregory Smith directed the episode written by Phil Klemmer & Marc Guggenheim (#207)

Airing Thursdays at 8 pm ET/PT on The CW -- until January 24, when it shifts to Tuesdays at 9 pm — "DC's Legends of Tomorrow" stars Arthur Darvill as Rip Hunter, Brandon Routh as the Atom, Victor Garber and Franz Drameh as Firestorm, Caity Lotz as White Canary, Maisie Richardson-Seller as Vixen, Dominic Purcell as Heatwave and Nick Zano as Citizen Steel.