I'v been playing AP Ezreal thinking this rune would help my sustain. After a few games i realized it was doing nothing. Ezreals Q has always had the most weird interactions, i can't tell if its intentional or not.
TheLastShadow451 votesHis Q is counted as a basic attack and not a spell. It will proc all on-hits that you have but not spell effects.
AP Megaman1 votesIt procs luden's echo though...
TheLastShadow451 votesIt used to not, but since the rune update every champion with an ability like it has been able to. 
can also proc them because of the rune update.