Interesting non tier 6 key mastery choice Idea
For people with ranged cc e.g. fiddle, morg brand, maybe we could see a mastery where you gain x% ms toward a cc'ed target or a target you cc. It would help them follow up better on their cc and make neat plays.
Nothing worse than when the feared target walks out of fiddle ult. Or morg could land a clutch bind and quickly close the distance for an ult.
Possible alternatives you steal something like 1% of targets ms with slows or 2% with hard cc.