I've done some calculations for you here.
In the Ambush tooltip at lvl 20 it says: "Ambush the target, causing 133% weapon damage plus 55 to the target (192% plus 79 if a dagger is equipped)."
Shadowfang (BiS sword) does 29-56 damage, which equals an average of 43.
43 * 1.33 + 55 = 112,19...