Kayle mid isn't what you expect Kayle mid doesn't get much Ap but scales mainly off attack speed, and gets very strong because of her insane farming capability

I max her E by level 9 to get ahead in farms quickly, if you focus the caster minions, activate your E and hit each one once you should clear all 3 relatively quickly, you then cast your Q to last hit big minions and continue last hitting with your E, farming with Kayle is simple,

For the wraith camps I speed myself up to get there quickly then cast my Q on the big wraith and activate my E focusing the big one, doing this should make them all die at the same time by the AOE damage from your E