When all the good guys have been captured, it's time to round up all the former bad guys.

That's where Arrow is headed in its season finale tonight, which finds Oliver (Stephen Amell) teaming up with some of the series' former villains to take down Adrian Chase (Josh Segarra) and save his friends once and for all.

One of those bad guys is Slade Wilson (Manu Bennett) who's apparently been locked in an underground prison on Lian Yu for years. In this exclusive clip of tonight's finale, Oliver and Slade reunite, and Oliver finds that Slade's sanity has returned after his bout with mirakuru.

"Why do you want to help me, after everything I've done?" Slade asks, reminding all of us that he was the one who killed Oliver's mother, and that Oliver probably should have killed him for that.