Lethal Tempo
You wanna know why Lethal Tempo isn't doing well on most champions? It's not because it was doing 30-80% instead of 40-110% attack speed during its duration before the patch. It's because it takes 1.5 seconds to activate after damaging an enemy....
On paper it sounds good, but in reality, damage is too high ALL AROUND, and nobody is alive 1.5 seconds after damaging anybody. Either you or your target is dead already.
In today's environment, lethal tempo would only be good on an adc who has a robust tank or bruiser and their team isn't getting insta-deleted when being breathed on, which is too rare.
P.S. My dream scenario is that you offer some nice defense options and tweak the game to be less bursty and less snowbally like it was several seasons ago. In that scenario, the game will feel better, like it did long ago, and lethal tempo would actually proc in more situations.