Help with entity look positions

I need help with two things, that both involve being behind a target entity.
So, I'm making some assassin type weapons for my magic mod, and one involves a condition that will activate an ability when hitting behind an entity.

The second thing I cant seem to figure out is another weapon ability where when you right click an entity, it will teleport you behind the entity.
I really need help figuring out how to do these two things, since I dont quite understand all the look blocks yet and how to manipulate them.