Oh I see you posted while I was replying.
This would be practical if your deformations were in a fixed location but you would have to create a black/white mask to use as a tessellation multiplier for each section you wanted to raise. Though I’m not even sure you can use a texture in that channel. Then we get to the issue of connecting that to matinee or whatever it’s called in UE4 now. You would have to trigger the event and have an animated value fed into your material to smoothly animate a tessellation change.
If you’re doing the ground in it becomes much easier. If you are concerned with the silhouette of the raised bit you could duplicate the faces you wanted to raise, then extrude them forming their own separate mesh this would make the top of the raised part match the terrain it was raised from.