Episode one's buckets and buckets of blood
The Viking sequence hits hard, as only a cable television series could. The concept was, according to the show's visual effects designer Kevin Tod Haug, a push for "ultra violence, and then an added order of magnitude" designed by director David Slade (30 Days of Night). "It was played mostly for fun, if you will. The idea is that it's so active that you can't really take it seriously."
Where equally vicious series like Spartacus relied on computer-graphic blood to enhance action sequences, American Gods relied on old fashioned fight moves, carefully choreographed by stunt coordinator Branko Racki, practical dummies, and gore from makeup effects designer Christien Tinsley. Blood elements were produced using hydraulically sprayed blood bags filmed with a high speed camera that could capture every drip in slow-motion.
Digital effects were still required to bring a lot of the action together. VFX studio Mr. X Inc, known for work on the Resident Evil movies, came on board to finesse the blood splatters, add extra, flying flesh pieces for maximum carnage, and to insert CG weapons that would have caused action damage during shooting.
By using both practical and digital approaches, the shots have a much more visceral feel, according to Jeremy Ball, a visual effects supervisor on the show. "We tend to start with the prosthetics and push these as far as we can until they starts to feel rubbery or overly stiff, and then we either manipulate it or we replace them with CG," says Ball.