why do you people wish so much to copy dota spells? Don't you have any imagination?
for that you need a trigger with 10 if/than/else
each if should gave own conditions that contains unit state(% of life in this case)
so it would look like: 1 if 90%, 2nd if 80%, etc
than you add abilities +damage and attack speed, but im not how to remove all the mess that will apear.