Strangler

You have mastered the act of strangulation, and use it to your advantage. Once you gain this feat, you are able to do the following:

• When making an opportunity attack from behind, you can chose to choke your opponent. When you do, you grapple your opponent, and for every round your enemy is grappled, he is considered to be not breathing, and is dealt 1d4+1 force damage. Does not work on Constructs.
• When you take the above action, you can make a bonus attack with a dagger for every turn choking your enemy.
• You can use whips to choke your opponent. To do this, make a DC 10+ (target's Dexterity modifier) Dexterity Check. If you succeed, your whip is wrapped around your enemy's neck, and the same effects happen as if you choked your target (see above). On your target's next turn after being strangled with a whip, they can attempt to break free in the same manner as if they were grappled. Only works on creatures that are Medium or smaller and not Constructs.