Ok, so we have all seen this a hundred times before. A ghost or some kind of demonic presence tries to push itself into this realm and in doing so a wall gets stretched and takes on a kind of rubber look with an imprint of said horrid beastie, you know what I mean? If not google The Frightners…one of the earliest uses of that FX I can think of.
Any way I’d like to take a hi poly model and animate its appearance into the surface of a second object. How would you go about this in Blender?
Use a Shrinkwrap Modifier, with the target object as what you want it to change to, without seeing a blend file, or some images of where you have got to it is difficult to comment precisely. You can keyframe the influence of Modifiers over a range of frames so the first object gradually changes shape to the target. You will need to use a Subdivision Surface Modifier as well and a good topology for both objects.