Things are getting intense as the countdown to the Season 2 finale of "Arrow" continues. Now, in addition to coping with his mother's tragic death, Oliver Queen will also have to deal with his breakup with Sara while trying to stop Slade from destroying everything that he has ever loved.

The last episode ended with a shocking twist after Moira Queen revealed that she already knew her son Oliver was the Green Arrow. She and Thea were also kidnapped by Slade Wilson, aka Deathstroke, who forced Oliver to choose which person that he wanted to save. At that game-changing moment, Moira choose to lay down her life so that Thea could live.

Executive producer Andrew Kreisberg revealed that the next episode of "Arrow," which is titled "City of Blood," will begin with Moira's funeral, but Oliver will be missing in action.

"The next episode opens with Moira's funeral and Oliver is missing," he said, according to Hypable.com. "Her death has a profound impact on everyone in the series. It's certainly what's going to drive Oliver in these last three episodes, and it's going to drive Thea, not only in these last three episodes but also into series 3."

The EP also talked about why Moira was killed off the show, explaining that her death will serve as motivation for Oliver and Thea and that it was the culmination of her character arc.

"It was, 'If Moira wins the mayorship and if she makes up with her kids, what is she? What is Moira without a giant secret?'" Kreisberg said. "And if they all forgive her and then there's some other giant secret, for us, it felt like we were becoming a giant soap opera."

He added, "It really just felt like, in a way, she could die a hero's death and also die this person who was conflicted. Because even as she's saying, 'Hey, we have to tell the truth,' we're seeing that she's kept this other horrible secret. You literally can't change her."

The CW released a trailer video of "City of Blood," which leaves fans with a number of questions: What happens at Moira's funeral? Where is Oliver Queen? Will Thea leave the Queen mansion for good? Is Oliver planning to die in order to stop Slade? And to whom will Oliver disclose his Arrow identity?

In a batch of promotional photos, Oliver and Laurel are seen taking on Slade's masked army of superpowered soldiers, reports ScreenCrush.com.

The official synopsis of "City of Blood" states as follows:

"After Slade (Manu Bennett) threatens to take everything Oliver (Stephen Amell) loves away, Oliver decides the fastest way to stop further bloodshed is to surrender to his enemy. Knowing that surrender will surely lead to Oliver's death, Diggle (David Ramsey) and Felicity (Emily Bett Rickards) go to extreme measures to keep Oliver from confronting Slade.

"Meanwhile, Thea (Willa Holland) considers leaving town, and Laurel (Katie Cassidy) resumes her crusade against Sebastian Blood (guest star Kevin Alejandro). Finally, Slade unleashes his assault on Starling City."

In a recent interview with TVLine, Kreisberg teased, "There are a couple of flashbacks that are going to blow people's minds [by the end of the season.]" According to Entertainment Weekly, Nyssa al Ghul is one of the characters who will return to Starling City with a few friends to help aid in Sara and Oliver's fight against Deathstroke.

At the end of "Seeing Red," Sara stated that she was leaving town to visit "an old friend." The mystery has been solved: "She went to go get help," said Kreisberg, adding, "because when you're fighting an army, you need an army."

The EP added that the finale, "Unbreakable," will feature an all-out war in Startling City. "It's the Arrow, Canary and Roy and the League of Assassins versus Slade and his Mirakuru army for the city."

"Arrow" S2E21, "City of Blood," airs Wednesday, April 30 at 8 p.m. EDT on The CW.

Watch the official trailer below.