I could go into a long drawn out post explaining the exact mechanics of this ability, but I know it will never get read, so i'll just be blunt.
This is my idea for a new Shadow Priest ability.
Cloud Mind -
There is a Shaman and a Warrior charging towards a helpless Shadow Priest.
The Shadow Priest casts "Cloud Mind" on the Warrior and now the Warrior cannot see him.
The Shadow Priest is stealthed ONLY to the eyes of the Warrior. Now the Shadow Priest can deal with the Shaman.
It would be a magic effect, and last 30 seconds with a 3 minute cooldown.
It's a new form of CC. It's a magic effect so it can be dispeled easily.
What do you think?