The dark gray skin proved another challenge given that so much of the film takes place in darkness. "We did a combination of a makeup pass, which is almost like a dry brushing over it, and then just finding places where you need to pull out some of the highlights so it has the modeling you need to be able to read in all the shots," Clark explains. "We played the skin like a rotten, mummy: nothing too moist, with a lot of wear marks on it."

The fight choreography offered placement challenges as well. Leven was sent to Shreveport, Louisiana, where they were re-shooting the third act. "There was going to be a fight scene and they sent us back some cut footage of the stunt team and it was a full-on wrestling match with a lot of hand-to-hand grappling," Clark continues. "So we had Nicolas Cage and Ron Perlman in the main part of this fight and we matched the placement of the stuntman standing in for the demon.

"But Ron Perlman's character has a signature move (a bear hug and then he rears back with a head butt) that was challenging to work with. At one point he tangles with the demon, which does a 180 in his grasp and they're embracing and Perlman does the heat butt into the demon, which doesn't react. And then the demon envelops him in the wings and there's a blast furnace of fire that engulfs him. We had to figure out how to achieve this effectively and economically? We did this with a combination of covering his face with little licks of flame coming up from underneath and did some 2D comp coloration changes of his skin starting to darken. We didn't want to get too grisly, since this is PG-13, so we covered him pretty quickly with flame and played the rest of it out with internally lit flames with shadowy shapes."

There's also a partial transformation sequence that necessitated facial work by Tippett. This was supervised by Leven in collaboration with Aharon Bourland, Tippett's CG supervisor. This was achieved with a blend of warping and coloration techniques. Some of the shots in the sequence were actually shared with UPP in Prague, which previously worked on plates and so there was some back and forth to attain proper continuity.

The final challenge was the death of the demon. Tippett had boards with a rough outline and empty plates with superimposed shot descriptions provided by others. "Figuring it out wasn't easy," Clark says. "We came up with something after conversing with Adam using movie terms and old film references and then turned around and explained it to everyone else in terms they could understand. It was the last shot that we finished, right up to the wire and quite an ordeal. It was a huge assembly of comping elements and animation. The demon turns and explodes and the apparition goes up through the ceiling. We did something inspired by Hellboy where we concentrated on the buildup: the demise of the demon was triggered by the reading of a verse from the book. We built it over a series of shots so it doesn't just happen in one shot. We had little patches on the demon that start to crack and result in a glow that looks like it's burning from within. It turned out pretty well. It's always difficult trying to come up with something that doesn't look too familiar."

Bill Desowitz is senior editor of AWN & VFXWorld.