Theres really just a priority list you have to go through inside your head its so situational, sometimes you have to use it to dodge an ability, sometimes you have to use it to gapclose...sometimes you have to use it for the slow, sometimes you need the damage...generally you just try to check as many of these boxes as you can at once and you need your e around 5.5ish seconds cd to be able to e>combo auto twice then zhonyas and your e will be back up after, thats about as much time as you'll get in most teamfights its barely enough time for you to not lose all ur hp