Arrow season 3
Oliver Queen becomes Al Sah-Him - new leader of The League of AssassinsThe CW

Arrow season 3, episode 21 titled, Al Sah-Him, airs this Wednesday and fans will finally get to see Oliver transform into the League of Assassins leader.

The upcoming episode's official synopsis reads: "Oliver goes through a rigorous transformation. The League of Assassins sets their sites on Nyssa (guest star Katrina Law), who is back in Starling City training Laurel. When Nyssa realizes they are coming, she arms up to face them alone but Laurel asks Felicity and Diggle to help protect her new friend."

In last week's episode of Arrow, Oliver gives in to the demands of Ra's al Ghul and agrees to take up his position as the new head of the League of Assassins. Thea, whose life is restored in exchange for Oliver's allegiance to the League, emerges from the Lazarus Pit with no recollection of her brother's return from his life as a castaway, as well as failing to remember that their mother is dead. (via Melty)

The show's executive producer Marc Guggenheim told E! News that Team Arrow will struggle to move forward without Oliver's leadership and accepting his current situation will be a lot harder for them as compared to what they went through when they thought he was dead (post the midseason finale episode).

"Knowing that he's out there and alive, but a member of the League of Assassins, that's a whole lot harder. I think [episode] 21 is one of our most emotional episodes because-I'll spoil a little bit of 21 and say-21 is a villain of the week episode, and it just so happens that the villain of the week is Oliver," he said.

The showrunner also addressed the question of whether or not there is hope for Oliver to return to being a vigilante.

"The last three episodes spend a lot of time addressing the question of is there hope for Oliver?" Guggenheim says. "Is there hope for Oliver in Felicity's mind? [Episodes] 21 and 22 have some very specific things to say about that, and Felicity's coming to grips with the conclusion of episode 20."

Speaking to TV Line, Guggenheim also teased some trouble for Diggle in this week's episode. "Something happens in Episode 21 that really upends Diggle's world, certainly vis-à-vis Oliver. That's something that will have repercussions for the remainder of the season."

Arrow season 3, episode 21, Al Sah-Him, airs this Wednesday, 29 April at 8pm ET on The CW. You can watch the episode online on The CW website by clicking here.

Or, you can click here to watch the episode via live stream online.