Arrow executive producer Andrew Kreisberg teases what fans can expect from tomorrow’s season 2 finale, titled “Unthinkable.” Spoilers ahead.

Embracing destinies

In the season finale, “Everyone is really faced with a choice about who they’re going to be,” Kreisberg tells GreenArrowTV. “[F]or Oliver, all season long, it’s been a question of ‘am I a hero or am I a killer?’ For Thea, she’s certainly presented with two paths before her. ‘Am I Oliver’s sister, or am I Malcolm’s daughter?’ Sara, ‘Am I the Black Canary, or am I one of Ra’s al Ghul’s minions?'”

These character moments will be interspersed with a “giant, epic battle” that is “probably as big as anything we’ve ever done in terms of scale, in terms of action, and in terms of visual effects.”

Kreisberg also teases “a couple of ‘big Olicity moments’ that I think fans are really going to appreciate,” adding that Felicity “does one of the most brave things she’s ever done in the course of the series, and certainly one of the bravest things we’ve ever seen anybody do in the course of the series.”

Slade’s rage

As our heroes grapple with embracing their destinies, we’ll also learn more about Slade’s vendetta. “Yes, the Mirakuru obviously unhinged him, and yes, it allowed him to so subsume his moral center, that he was willing to essentially destroy the city just to make Oliver suffer,” Kreisberg says.

“But at the end of the day, I think there are some very human emotions, and I think when people lose someone that they love, they’re looking for somebody to blame, and unfortunately, all of his rage and anger went right on to Oliver.”

The EP calls it a “sad realization” for Oliver that the “rage that was inside Slade was not entirely sci-fi evil juice-generated.”

Armies colliding

As for the many guest stars showing up, Kreisberg says the League of Assassins and Suicide Squad were introduced this season because the writers “knew from the very beginning that Slade’s agenda was going to be to make an army like himself, and that they would take on the city, to give it a different, ground level, visceral scare, as opposed to the earthquake device in season 1.

“So if you’re facing an army, you need an army to fight them.”

Arrow season 2, episode 23, “Unthinkable,” airs Wednesday, May 14 at 8:00 p.m. ET on The CW.