when i was levelling mutilate (62-69) i did the following:
CS -> Mutilate, wait 7 seconds, KS -> 2X Mutilate, if it was still alive finish with envenom as it would be 5/5 at this point.
envenom isn't a bad ability, but you lose a lot of damage having your DPs drop off. its a little better now, but personally i think it should really only be used to finish things off.