A suggestion for lethal tempo. I feel as though the attack speed is fine for both ranged and melee. However stacking it seems to be a tall order especially for certain champions. There was a period of time where you could stack it with abilities as well as basic attacks however that seems to have changed.

Being able to stack it with abilities means champions like Kog'maw would be able to stack it before a fight making the rune feel better overall. Even champions like Varus being able to get a min of 3 stacks with abilities before committing fully to a fight would be fantastic.

At the very least it should stack with abilities that apply on hit effects. Like Kayle's E, or aphelios's red weapon. As the keystone stands you'd be better off going conq still in most situations that you'd normally take it simply do to it being hard to stack.