The CW has released the official synopsis for season 3, episode 18 of the CW show, Arrow.
The title of the episode is “The Return” and it features the return of Manu Bennett as Slade Wilson/Deathstroke and Colin Donnell as Tommy Merlyn. Check out the official synopsis:
“THE RETURN OF DEATHSTROKE AND TOMMY MERLYN — Malcolm (John Barrowman) puts Oliver (Stephen Amell) and Thea (Willa Holland) in a dangerous situation that lands them on Lian Yu with Oliver’s former enemy, Deathstroke (guest star Manu Bennett). A flashback reveals when Oliver and Maseo (guest star Karl Yune) returned to Starling City to retrieve the Omega bio weapon, and despite being under strict orders from Amanda Waller (guest star Cynthia Addai-Robinson) not to reveal himself to anyone, Oliver looks in on his family, Laurel (Katie Cassidy) and Tommy (guest star Colin Donnell). Dermott Downs directed the episode written by Marc Guggenheim & Erik Oleson (#314). Original airdate 2/18/2015.”
Source(s): Green Arrow TV
