If HBO’s “The Last of Us” wins the Special Visual Effects Emmy, it will be for pulling off the horrifying Kansas City clicker horde and Bloater attack toward the end of Episode 5. That’s where Joel (Pedro Pascal), Ellie (Bella Ramsey), Henry (Lamar Johnson), and Sam (Keivonn Woodard) heroically escape the escalating battle in the cul-de-sac, in which Kathleen (Melanie Lynskey), Perry (Jeffrey Price) and her militia are attacked by hundreds of swarming clickers and the bloater: the biggest and baddest of the Cordyceps-infected victims.

Wētā FX did the creature work on the CG clickers and bloater (led by animation supervisor Dennis Yoo), in addition to the gunfire, destruction, and explosions, including the fiery sink-hole from which the creatures emerge. All told, it was close to 400 VFX shots.

“We had different stages of infection within that sequence,” Wētā VFX supervisor Simon Jung told IndieWire. “So there were runners: that’s people that are freshly infected. And then the clicker is a more advanced stage of infection, and, I think, it takes about 20 years or so of infection to reach the [bloater] level, which is very advanced and very strong. So we had to build different characters for that purpose because we had the live-action ones on set and we just augmented in some cases or added more to it.”

Wētā designed eight stages of clickers, which they scanned and then did photogrammetry passes of on set. Off those, they built variants for size, scale, ethnicity, and wardrobe. That provided a substantial library of clickers to flesh out scenes as required, particularly the high and wide shots where we glimpse hundreds of them running. This was accomplished with some motion capture on set in Vancouver along with more extensive recapturing sessions at the Wētā stage.

“We used mostly those performances because we could make it a lot more specific to the shots that we had,” Jung added. Wētā used the latest version of the Massive crowd software for the key shot of the hundreds of infected creatures emerging as an amorphous mass out of a sinkhole.

Many of the creatures were full CG, some work involved head replacement, and others were augmentation of the mushroom growth on the head. “For those that got really close to camera, they were built to a very hero level, and they had all the subsurface [scattering] and all the other things that you need in order to make those look realistic. And then we had a next level, which was a little bit further away from camera, which still allowed for cloth simulation and any type of simulation to put on top of those.”

It helped that the battle took place at night and that the first wave attack had so many quick cuts. “For example, when they first burst out of the sinkhole, that first wave is all CG characters,” said Jung. “The second wave that you see behind them are the ones we filmed on set and are completely made up and recaptured. We also added more of the rebels that were shooting at them to fill out the scene and make it look more epic with our CG characters.”

The most important directive from showrunner Craig Mazin was that the attack needed to be absolute mayhem with frantic action happening everywhere and people going down in all directions. It was choreographed chaos.

But one clicker was created especially for the series: an acrobatic child clicker (played by actress/gymnast Skye Belle Cowton) who chases Ellie into a car. Although Ellie eludes her, the creepy clicker eventually finds bigger prey in Kathleen.

“We kept the on-set performance,” said Jung, “because it was great the way she entered the car in a roly-poly type movement. So we hung onto all of that. The main thing that we had to change was she wore a prosthetic on top of her head and it made it look really big, and it became unclear that she was a child. So there was quite a long design process to figure out how we can sell that she’s a child and hang onto those child-like proportions. The pigtail helped with that and so did the braces. She had to really look menacing.”

When it came to the bloater, whose design was greatly influenced by the creature in the videogame, showrunner Neil Druckmann of Naughty Dog was adamant that its appearance and movement looked cinematic. The body is piles of fungi and slime mixed together and the head is incredibly sunken.

“There was prosthetics and a full body suit [from designer Barrie Gower] that had been done for a really big actor [Adam Basil], and it looked great,” Jung said. “We just had to free up the performance of him a little bit in order to get slightly more dynamic behavior and add some more weight. So we initially built a CG asset of the bloater on set.”

But then it was decided that the movement was not realistic enough because of the prosthetic suit, so they replaced Gower with a CG bloater. “We took the model that we had and changed the proportions quite a bit,” added Jung. “From there we got additional artwork from the Naughty Dog crew for the sunken aspect of the head, the bloom on top of the head, the freaky mouth, and the arms. We were able to reinvent the fungi material with simulation. Obviously, they wanted this to be the most monstrous version of the bloater because it’s the boss.”

While the bloater tears the head off Perry, Wētā initially prepared a different grisly act: ripping the guy in half. Unfortunately, it never looked right. “That took a lot of time to get the motion just right,” Jung said. “It looked comical with his spine hanging out or too clean. So we looked at the bloater’s behavior in the game and found this moment when he grabs into the jaw and just rips the head in half. It took a while to crack that and we refined it from there.”