Updated model with correct shading and better topological edgeflow, and with a poly count for just the face.
There are 1533 polygonal faces not including the headdress, eyes, or teeth.
Maleficent looking condescendingly amused
Polygon counts (by face):
Each Eye: 400
Each Set of Teeth: 832
The main parameters that would be needed to easily deform Rafiki’s face are the jaw, the brows, and the nose. The brows are very expressive, going up to show the whole eye for the excited face in the first example, and going down very far for the look of deep contemplation in the second example. The jaw morphs drastically from the first image to the next, going from two distinct sections of the upper and lower mouth (the skull and the mandible) to a small, almost unseen slit in the second. It would be hard in a 3D model to hide the teeth in from the first pose to the second due to the wild variation in the shape of the jaws. The nose stretches a lot from the first pose to the second as well, due to the exaggerated squash resulting form the open mouth and the exaggerated stretch from the lip going down. The lower eyelids are also a consideration because they define the shape of the eye in the expression, and the pupils would also need to be able to move. The hair could probably just be an afterthought if modelled accordingly- since I used modified volumetric cones, cubes, cylinders, and spheres it was harder to get them in the right place according to the picture. The hardest part to work with would probably be the closing of the lips around the teeth, transitioning into the smaller mouth shape of the second posture.