Idea for a support gem enduring inspiration

I had an idea for a support gem that could be usefull for active skills that have a duration and i want to share it here. Maybe the math behind the skill is not optimal, but i would like a mechanic like this.

- The gem could have a name like enduring inspiration.
- The gem can only support skills gems that can hit.
- When the linked gem hits, it has a 100% chance to grant 30% additional duration based on the maximal duration it has.
10 sec max duration -> hit -> now 13 current duration
- Everytime the skill hits, you gain a stack of enduring inspiration
- Every stack reduces the chance to grant additional duration bei 10%. So on 10 stacks the chance for additional duration is 0%
- On reaching 10 stacks all stacks disapear and the duration of the active skill gem ends immediatly
- Every stack of enduring inspiration grants 2% more Damage

The gem is a bit like the inspiration support where you can get stacks and buffs. But here we gain a bit damage and more duration.
Im not sure about the math, but it should be possible to get more duration then before or maybe less.
I thought to use it with summon raging spirits or blade vortex. Maybe static strike.
When you reach all 10 stacks the skill ends really fast on skills that hit very fast, but it should be possible to make the duration at all longer.
I doesnt thought this through, but something like this would be cool.