I belive Aftershock needs to decrease your own damage

I always imagined Aftershock as this hyper tank rune that makes you unkillable for a few seconds. But when champions like Riven use Aftershock to become unkillable in trades i go D: I think Aftershock should have a built in reduction to your own damage while giving you even more Armour/Mr What do you think Boardes friends