It can be hard to reinvent the wheel after a decade and a half of content, but Greg Nicotero is going to try. The Walking Dead: Daryl Dixon executive producer spoke to Entertainment Weekly about a new brand of zombies introduced in the second season of the spin-off series. Entitled “The Book of Carol,” the upcoming batch of episodes will finally reunite best friends Daryl Dixon (Norman Reedus) and Carol Peletier (Melissa McBride) after they bid farewell in The Walking Dead series finale.

McBride was slated to appear in the first season but couldn’t commit to the shooting location in Europe. Now, however, Carol has become hip to Daryl’s kidnapping and will stop at nothing to save him. Evidently, she will have her work cut out for her. Nicotero explained to the outlet his vision for bioluminescent zombies, which he will debut in the new season. As always, the makeup effects master highlighted practical effects in these new glowing monsters.

“During the strike, I came back to the States last year, and we were talking about the bioluminescent zombies. And 70 percent of that was practical effects. We had LED lights, and we also had this black light wildfire system where we would paint the backside of silicone prosthetics with a black light-activated bioluminescent paint. And if you watch the outtakes of that scene, you’ll literally see my team standing there with black lights right on the zombie’s faces.”

Nicotero used visual effects to make the cave walls glow. But even with this addition, there were some complications with bringing these zombies to life.

‘Daryl Dixon’ Had Some Challenges With Bioluminescent Zombies

Practical effects always look better on film, but they have some drawbacks regarding production. Nicotero noted that filming the new walkers could only be done for a few minutes at a time.

“We did stuff where we were able to make the inside of the mouth glow. So a lot of it was just hiding stuff, not only in the wardrobe, but then underneath the skin, painting the silicone appliances from underneath, painting some stuff on top. And then you knew that once you would charge it right before the take, you would have probably 120 seconds of really strong interactive light before it started to fade. So there was a lot of running in, and charging it, and coming out, and then VFX just sort of amped it up.”

This labor of love is necessary for a horror series that needs to keep reinventing itself. Daryl Dixon is inherently a different show from its predecessor. Filming on the European coast even gives the visual aesthetics of the series a reboot. To stay fresh, Nicotero and his team keep pushing the envelope, so this well-treaded territory remains interesting. Fans can see these walkers come to life when Daryl Dixon Season 2 premieres on AMC on September 29.