Rengar Ferocity
Aatrox, Tyrndamere, Mordekaiser, Renekton and Gnar each have a resource that builds up while you're fighting, but when you're out of combat for too long that resource starts to fade away and you have to build it up again
Why then does Rengar's Ferocity never diminish no matter how much time passes
Rengar can build up ferocity, go back to base to heal and buy items, then return to the lanes and engage his full combo, but the others would have lost all of the resource they built up
I just think he should lose a small amount of power if he leaves combat for an extended period of time, maybe losing a charge of Ferocity every 10 seconds when out of combat