Adaptions are changes to the human body, they can help to make assasins faster or stronger or more acurate, they fall into four catergories.
Limited control over one or more elements
Better sight, smell, or taste, basicly anything around the senses
Increased strength, speed, swis army knife hands, that sort of thing
Telekinisis, telepthy, that brainy stuff
These are just examples, you can make whatever you want, within reason.