Dorans shield makes a miracles with your passive. All the time when You are on mid vs ranged champ they try to harrass you with basic attacks. With dorans you will not care of that.. Cuz u will heal instantly so they can ssuck Your D***.. :D on lvl 5-6 You will destroy your opponent just try not to die earlier. In mid - late game NEVER ! I repeat.. NEVER engage with your E...
(And belive me i saw many players does that kinda **** and then they have no way to escape when they are losing a fight...) FIrst push W for better engage then Q if u need only to harras b4 u kill some1 just use it and escape safely with your E. When you try to kill some1, w8 with your E for critical moment (for example when Ezreal uses his ult.) to dodge it and then kill him without problem. GL HF