"There's also Kreacher and Dobby. Framestore has taken over the work of Dobby from ILM and we've updated the look subtly; and I think we've done some pretty nice character animation. I was very keen to bring in some more human characteristics for both Dobby and Kreacher [also done by Framestore] just to help the believability. For performance, we got Toby Jones back as Dobby and Simon McBurney to play Kreacher and we were very keen that they should be directed by David at the time of the scene to be filmed and not leave it as an afterthought. So it allowed David and the other principals to develop the scene with them."

One of the biggest challenges for MPC (which created more than 180 shots, under the supervision of Nicolas Aithadi) was the transformation sequence. The concept artists explored different combinations, blending features, sizes and skin textures from Harry and the other characters to create the hybrid designs. A custom rigging system was used to blend the data from the facial capture shoot, allowing animators to keep control of the fine details.

Once out of Privet Drive, the seven Harrys fly over London to escape the Death Eaters. MPC had to create CG thestrals: a cross between a horse and a dragon and extend Privet Drive's set. Greenscreen rider elements were combined with the CG creatures, digi-doubles and live-action footage. For the Death Eaters' chase, MPC created more than 100 CG characters, including full screen digi-doubles for Harry, Hagrid and the Death Eaters. The environment work included a CG aerial cloudscape, cityscapes and various set extensions. The chase culminates with a wand duel between Harry and Voldemort, with vfx encompassing explosions, wand effects, CG water and the bike crash.

The 3D team re-rigged and textured Nagini and animated it following the dynamics of vipers, cobras and pythons. Nagini attacks Harry in Bathilda Bagshot's house, biting him and wrapping itself around Harry. For this sequence, MPC carried out body replacements to enhance the interaction between Harry and the CG snake.

Framestore (under the supervision of Christian Manz) keyframed Dobby and Kreacher, and to soften their features the team used the elves' original topologies from which to base the makeovers. Dobby's neck was smoothed out, his arms shortened and his eyes were made less saucer-like; Kreacher's nose was shortened, and ears were trimmed. They built on their recent skin shading technology, using multiple subsurface scattering techniques. To light scenes, they used mostly "bleed" cards of HDRI textures from the set projected on cards. That created a less diffuse style of lighting than they have done in the past.

Additionally, for the story-within-the story fairy tale, The Tales of Beedle the Bard, Framestore animated a crucial three-minute sequence directed by Ben Hibon and led by Sequence Supervisor Dale Newton. The Commercials team used the influences of stop-motion silhouette animator Lotte Reiniger and shadow puppetry from India and the Far East. Added to this was the modern aesthetic of the single flowing shot. Working in Maya, Hibon and Newton created the story's characters, emulating the rigidity and motion of Reiniger's hand-cut paper silhouettes.

For the Burrows, Double Negative (under the supervision of David Vickery) created several different lighting styles for full 3D environment extensions. In addition, the location was much more prominent in this film, seen in many more shots and sequences, and it was immediately decided that a way had to be conceived of reducing the rendering time, in accordance with the volume of work. To extend it out into the distance, this ended up being a 2.5D environment, with the team rendering out multiple series of 3D dynamic elements to cards, which were then placed in 2D and layered up to create the illusion of depth.