Riven and the BlackCleaver.

Im not talking about nerf riven. Im talking about the + , she can apply full stack of Amor reduce in like 0.75 seconds. Can we let it only occur every 0.75/0.5 seconds instead? Cuz i dont want Tanks to be killed so fast. The same happen to , but with riven, i think she need to aa more before she ult instead of killing tank in 0.75 seconds. I want for fighter, not for assasin.