Sneak Attack

If target you attack doesn't see you or is confused by any means you may roll additional Xd6 on attacks.
Every other level increases number of d6
Lvl1-2: 1d6
Lvl3-4: 2d6
Lvl5-6: 3d6
Lvl7-8: 4d6
Lvl9-10: 5d6
Lvl11-12: 6d6
And so on...