Stormraider? What it is supposed to be

I do feel we still need more of this mastery, I know it is some times hard to proc, sometimes it isn't.

I know it is a good mastery, yet it doesn't feel solid or constant for what it should do or it's theme and the role it should play; deliver tons of damage and run from sticky situations, or CHASE!

We are up to the next preseason and I don't want to see this keystone erased;

Proposal: converts a % of the damage dealt to enemy champions into movement speed (with the proper bonus resistance to slows), this is not a direct rate to raw damage but more about %life taken down (as it is now), the movement speed can scale up to to 40% (or any value Riot decides is balanced), it is hard to get the full bonus just from dealing damage even for assasins, the movement speed may decay quickly. Killing an enemy champion, a legendary monster or taking down a turret will deliver the full bonus with no movement speed decay over 2.5 seconds.

In this way this mastery commits to its fantasy and a ROLE; taking down targets and chase, or commit to taking objetives and run (or steal them). I do believe this mastery needs such rework because this mastery was intended for assasins yet it is not used by them as they stick to pure damage instead to secure kills, if this mastery is updated in this way with the assasin rework we might actually see it shine.

If the mastery would allow you to do these things (or role) better, would you use it?