How to do smooth animation warping between a character and an enemy e.g. counter attack in Assasin's Creed

Another example could be killed from behind or any special move that you do that requires animation in player and enemy (Attack and reaction).

How you can make the player be right in the correct spot without teleporting the character or enemy right away. I just need the basic tools and functions to be in the right way. Not the full answer because I know it is complicated.

I already did my research and I think I can start with something but I don't know how to do it in the most efficient way.

Here is a video where it talks about that theory: https://youtu.be/Zltb4TSKKv0?t=9m36s