Assassin

"'Kill a man, and you are an assassin. Kill millions of men, and you are a conqueror. Kill everyone, and you are a god.'""-Beilby Porteus"

Information
The Assassin perk doubles all damage done to unalerted enemies. The effects of a Stun attack are usually multiplied by 1.5x.

Ghosts and Nyn all have this perk inherently.