In the “I Am Legends” episode of The CW series Legends of Tomorrow, the 24-hour immortality that the Legends received after drinking from the Chalice doesn’t quite go as planned. And while they’re stuck at Constantine’s (Matt Ryan) house in London as a zombie apocalypse is unleashed, Astra (Olivia Swann) must answer for a promised favor that could throw a wrench into even her plans. During this 1-on-1 phone interview with Collider, actress Olivia Swann talked about the fun of never being prepared for what the Legends get into, finding her place among this …