When Reign shows off what she’s capable of on Supergirl in season 3, expect to be shocked by what you see, according to Martian Manhunter actor David Harewood. So far, the new season has dealt with the fallout of the failed Daxamite invasion, the emotional and physical effects of which have lingered for those calling National City home. In addition to Mon-El’s departure, which meant the end of his relationship with Kara, Lena Luthor’s last-ditch effort to make Earth’s atmosphere uninhabitable to the invading aliens has since been turned into a smear campaign by villainous industrialist Morgan Edge (Adrian Pasdar). While the show is picking up the pieces from season 2, it’s also been sowing the seeds for the season’s real threat in worldkiller Reign — Odette Annable’s Samantha Arias — who has just begun to realize her true nature.

As you may have expected, that nature isn’t going to be a very friendly one, a presumption that was confirmed by Harewood, who shared his first impressions of what the character will be capable of during a recent Supergirl set visit attended by Screen Rant. Harewood teased that J’onn J’onzz will encounter the worldkiller at some point, but while that perhaps isn’t too much of a surprise given the character’s prominence in the series, the actor did mention how taken aback he was when seeing what Reign is capable of.

While staying away from specifics, Harewood summed up his thoughts on seeing the character’s actions for the first time, and from the sound of it, Reign won’t be pulling any punches. Harewood said:

“Yes. Gonna see some real J’onn J’onzz magic coming up in one of the fights. But she’s very strong. I was surprised at how well she can look after herself. But she’s full of surprises and I think audiences are going to be — first of all, when I walked on set the other day, I was shocked at what I saw. It’s a pretty arresting sight. Reign doesn’t exactly treat anyone with kid gloves.”

Season 3 has been a slow burn so far when it comes to the depiction of its Big Bad, and that approach is working for the series so far. Samantha’s gradual progression into the worldkiller makes for a different kind of arc for Supergirl’s big villains, who have typically shown up fully formed and ready to rumble with the Girl of Steel. Giving Reign a significant portion of the season 3 storyline to realize her full potential — vicious though it maybe — will hopefully make for a more gratifying watch for viewers.

If Harewood’s reaction to Reign is any indication, Kara and viewers alike are in for a foe unlike any they’ve ever seen. After the invading aliens of season 2, whittling Supergirl’s primary foe down to a single character who made quite an impression in the comics should make for a memorable and shocking conflict as the season continues.

Next: Supergirl is Heading Back in Time

Supergirl continues next Monday with ‘Midvale’ @8pm on The CW.