Here's the official description for Arrow season 3 episode 20, "The Fallen" - airing April 22nd.

Season 3 Episode 20 "The Fallen"

BACK TO NANDA PARBAT

Ra’s al Ghul (guest star Matt Nable) finally makes Oliver an offer he can’t refuse. The team joins Oliver on his journey to Nanda Parbat where a heartbroken Felicity decides to take matters into her own hands.