Is it possible to somehow put percentage in this instead of only raw damage?

image post
So instead of 1x1, I'd like to put something like 10%
The reason I am not using thorns aura is because it only affects melee units.

image post
So instead of 1x1, I'd like to put something like 10%
The reason I am not using thorns aura is because it only affects melee units.