You are not getting the point. Lightning main was using the killing intent passive which resets the cooldown of the mystery when a sword user kills a unit, either a ninja or a clone, and since you were probably using clones with your wind main he got reset . And the reset only applies when his myst kills a unit, not his standard. And its impossible for shisui to usee his myst round 1 so gaurantee you that didnt happen. So round 2 shisui used his myst and killed a unit, either a wind main clone or a yagura clone, then he got reset, next rounds if he killed a unit again with his myst he would get reset, thus allowing him to use myst every single round that a unit got killed.