Not sure about the numbers, but i just want more stuff to interact with charged abilities )
I was thinking about adding the "+ n% Faster time between charges", but decided agains it.
Also will need some kind of an indicator to see how much stacks you have.
How this will work(example on talon):
Using your Arrow for the first time you get a stack and take no damage. Using it the second time you take 5% damage and get another stack(you now have 2 stacks, and your spirit lifesteal gets reduced). Using it for the third time damages you for another 10% and gives you another stack, and so on. Each stack will last 8.5s(without any other items "Charget Shot" CD is 17s) Getting cooldown reduction also decreases the debuff time.
Basically spaming abilities takes more and more health from you(at 4 abilities you would lose 30% max health).
Also i am not sure if Spirit Lifesteal reduction is necessarry, but i added it just to be safe.
The self damage might need to be more(Because it is spirit damage, and gets reduced by Spirit resist)