Suggestions for stormriders surge

I had an idea for stormriders to basically make it the designated kiting mastery, first thing would be to have it apply a partial effect whenever damage is dealt, similar to how works now but applying to multi target spells as well, and being modified based on how what % health you just dealt, capping at 30% health dealt for the full 40% movement speed.

The second potential change is to have the % speed increase reduce the cast time of abilities similar to how attack speed interacts with a champions attack frame. This may take some balancing and probably shouldn't be a 1:1 ratio but it could really set stormriders up to be an attractive keystone choice.