how to counter your enemy while he miss all hes skillshots and still kills you.

i just played in another account as a vayne adc and an enemy rengar just oneshoted me but the best part was that he one shot me with out doing the one shot combo he just q and kills me he dealted 1600 dmg with a single q no crit and 3000 k with crit honestly this game is made with no counterplay or skills needed to kill your enemys and no defensive items thats why i hate new league and im sure that if you die by a champion like this you will feel the same feeling like me.