This is an intriguing development. Stephen Amell has shared a photo on Facebook of himself and Deathstroke sat on a bench, noting in a comment that the photo is from today. Currently, they are filming the eighth episode of the season – which also happens to be the 100th hour produced.
Given that the DCEU are using Deathstroke in their upcoming movies, and that Manu Bennett has repeatedly spoken out against Arrow since his last appearance in season three, this is extremely surprising.
The important question: How will he come to be in the episode?
Source: Stephen Amell on Facebook