Unity 5.3 outline and masking (image attached)

Hi guys,
im working on a 2d game and have 2 questions: (demonstration image attached)

  1. i have a game object with a sprite renderer and a sprite attached to him (the mountain).
    when an enemy (ball) collides with that game object, i would like to distract a hole (or some other shape) from the mountain at the collision point.
  2. i want to keep the outline of the mountain

what is the best approch to do the distraction and the outline?
code examples are welcome :]
many thanks!

Outlining and masking of sprites are not currently features in Unity.

Various assets on the asset store can extend Unity to do this though.