Mortal Blow

Is Mortal Blow affecting the Crit Rings 1 hit kill effect? Cause it would seem highly improbable to have multiple 1 hit kills in a mob, specially on the first hit. If it is affecting it, 21% 1 hit kills is beast.

I've been getting increased kill shots with Blast as well with my Critical Ring. I think anything with a possibility of a kill shot is added to by the rings anyway. Seems that way.