Domination Rune concept.

I just like making thins, here is a rune i made. any feedback is appreciated.

Domination: Overkill---------Cooldown: 35's-15's

Upon damaging an enemy champion bellow 60% health a timer will begin that ends after 4 seconds. While the timer is active you gain 20% adaptive penetration against that target, this amount is lowered by 5% for each additional attack against the target, total minimum -5% If the target falls below 27.5% health before the timer ends, the timer stops then the bonus penetration is carried over for 2 additional seconds and your next single target attack deals an additional 30 (+100% leathality) (+100% flat magic penetration) increased by 1.3% per 0.1 second remaining of the timer in adaptive damage.

Cooldown begins when the timer starts, If another attack isn't issued on the target within 2 seconds of the timer beginning then the runes effects end and the cooldown is reduced to 4 seconds.

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