Twin Stab

"Twin Stab" skill:

With this skill, the powerful thief can leverage his initial damage when backstabbing the victim. If the thief lands a successful backstab he will have an opportunity to use his offhand piercing weapon to thrust it in the back of his/her victim as well. Since the Twin Stab makes use of the offhand weapon it is not as powerful as the intitial backstab.

The Twin Stab tome is found in the Haunted House inside of the Midway. One must make their way into the small town inside of the Haunted House and find a boarded up window. Open this window to gain access to a small room. Search this room for a key. Once you have acquired the key you must find A Decrepit House and find a hidden exit. Make good use of your key, and enter at your own risk. On the other side you will find a chest with the Twin Stab tome inside. (A blood soaked book)

Note: The tome is a random load, sometimes you must try more than once to get one.