Wētā FX's work on Season 5 of Stranger Things spanned all eight episodes, amounting to 1,100 shots, much of which were featured heavily in the Upside Down. The studio contributed to a number of important parts of Season 5, including a digital replacement for Will Byers in the opening sequence of Episode 1 to match actor Noah Schnapp’s Season 1 age, and creating terrifying creatures, such as the slithery Vecna 2.0, the Mind Flayer and the Demogorgon that wounded Mrs. Wheeler and abducted Holly in the Episode 4. A highlight included work on the final battle, referred to as the showdown with Vecna and the Mind Flayer in the Abyss.
Martin Hill is senior VFX supervisor at Wētā FX and shared details on the studio's work on Season 5.
"The Pain Tree, where Vecna is holding the captured kids, needed to disguise the Mind Flayer in plain sight, with the big reveal only happening when our heroes, seemingly at the end of the journey, approach it," says Hill. "The creature’s final form needed to be immense, with the tips of the legs scraping the sky. We covered it in the Stranger Things language of vines, broke up the silhouette, and deposited sand and dust over it to embed it into the environment and give the sense of age and rootedness that belied the moving creature. This gave us interactivity of the dust falling and the vines snapping as the Mind Flayer starts to animate."
The VFX team referenced bone snapping in other parts of the series for shots with limbs hyper-extending, breaking and creating blood waterfalls.
"The scale of the creature is unprecedented and needed to be more solid than the smoke or flesh Mind Flayers of earlier seasons," Hill shares. "The creature’s exoskeleton is spider/crab-inspired, but not fully rigid, so we can see the secondary motion and slow, heavy jiggle that help illustrate scale, whilst residual vines swing from the body. The detailing of the model was essential for the scale, sculpting fine layered organic forms that feel like they’ve grown rather than been carved, making clear distinctions between the different materials of cartilage, bone, vines and shell."
Hundreds of articulated teeth and thorns were added and animated to increase the threat when close to the creature. Animators controlled the breath of the Mind Flayer, which in turn drove the simulation of dust and drool of the creature.
"The Mind Flayer has 22 legs that needed to work in sync and move naturally when the creature charges, without looking ungainly," notes Hill. "To achieve this, the animators needed to pay attention to the order of the legs’ motion, with differing legs having differing gaits in differing orders. The rigging needed to work so there were no collisions of the legs, whilst maintaining full flexibility in each of the soft tissue covered ball joints in the carapace."
Each leg impact was embedded into the ground, displacing vast amounts of rock and sand. These were simulated individually with the force of the collision. Pre-simulated aftermaths in the air and on the ground were mapped into the environment from previous shots of off-camera impacts.
Filming the actors within the scene took meticulous previsualization, which was used on-set through Toro, Wētā FX’s tablet AR tool. This allowed the filmmakers to see and compose shots with the animated Mind Flayer in place, helping with eyelines. The script called for a “sickly yellow hue” as the environment, which was developed prior to the shoot during previs and applied as a CDL during the shoot.