Good news, that click was worth it! Because the answer is yes, Deathstroke does appear to be returning, at least in some way.
It’s been over a year since the character of Slade Wilson was last seen in a season 3 episode, still imprisoned in Argus’s Super Max on the island of Lian Yu. As for the Deathstroke identity, it was more recently seen in an alternate future on Legends of Tomorrow, being used by Slade’s son Grant Wilson.
However, a new international cross-promo between Arrow, The Flash, and Legends of Tomorrow has been release, and in it we catch a brief glance of Deathstroke or at least someone in his gear:
The rest of the footage shown in the trailer is from episodes of the shows that have yet to come out, including a scene with Barry Allen and his mother, so clearly this is going to be happening in a few episodes. But the question is who will be under the mask, and why will he be involved all of a sudden?
It is possible that this could be Slade Wilson, and that maybe HIVE will be freeing him from his prison. From what we’ve seen HIVE would be strong enough to break him out. In the comics Slade has been associated with HIVE before, so it could make a certain amount of sense in this scenario.
Then again it could be some kind of Flashback for all we know. I wouldn’t get hopes up too much on that front just yet. We haven’t heard a peep about Manu Bennett, the actor who previously portrayed Slade Wilson, being anywhere near the filming. At the very minimum though we will be seeing someone in the Deathstroke gear soon.
Here is the the promo that a fan managed to post online.
https://www.youtube.com/watch?v=xVzvzf0b1lU