Oliver and Diaz go toe-to-toe for control of Star City in new Arrow promo Following last night’s new episode, The CW has released the first promo for Arrow Episode 6.20 which you can watch in the player below. Titled “Shifting Allegiances” and set to air April 26, the episode is officially described as follows: “RENE RETURNS TO NTA – Oliver (Stephen Amell) turns to an old friend to help battle Diaz (guest star Kirk Acevedo).