The next all-new episode of "Arrow" will be intense as both Oliver McQueen and Team Arrow adjust to his new position as the leader of The League of Assassins.

In the last episode of "Arrow," Oliver said goodbye to his friends and loved ones before taking on his new role as Al Sah-Him, Heir to the Demon, in the League of Assassins. However, before he left, he spent a romantic and passionate night with Felicity. To the delight of "Olicity" fans, the long-time friends and colleagues finally hooked up. In addition, Thea was resurrected from the dead after she took a dip in the Lazarus Pit in Nanda Parbat.

According to executive producer Marc Guggenheim, fans can expect to see Thea dealing with mysterious side effects now that she come back from the dead in the next episode.

"You can expect that there will be more consequences," he told E! News. "We established very clearly that the Lazarus Pit returns you, but not always in the condition in which you left, so there's a lot of stories to be told with Thea and her recovery."

The EP also teased that Team Arrow will struggle to move forward without Oliver's leadership.

"That's actually the emotional currency of [episode] 21," Guggenheim says. "The character journey of 21 is how the hell Team Arrow moves forward without Oliver and it's a different circumstance in 21, than it was in 10. In 10, they thought he was dead and in many ways that was a whole lot easier."

He continues, "Knowing that he's out there and alive, but a member of the League of Assassins, that's a whole lot harder. I think 21 is one of our most emotional episodes because-I'll spoil a little bit of 21 and say-321 is a villain of the week episode, and it just so happens that the villain of the week is Oliver."

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."

In addition, Guggenheim confirmed that Ray and Felicity's relationship is officially over.

Ray and Felicity are "pretty well and truly kiboshed," said Guggenheim, according to TVLine. "They do have a very meaningful exchange in Episode 22, but we're not going to do an on again/off again thing with them."

The synopsis for Wednesday's episode, which is entitled "Al Sah-Him," reads as follows:

"Oliver (Stephen Amell) 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 (Katie Cassidy). When Nyssa realizes they are coming, she arms up to face them alone but Laurel asks Felicity (Emily Bett Rickards) and Diggle (David Ramsey) to help protect her new friend."

"Arrow" Season 3, Episode 21, " Al Sah-Him," airs on Wednesday, April 29 at 8 p.m. ET on The CW.

Watch a promo video below.