Luden's Echo
I played a normal game on Ezreal playing mid and the Luden's Echo didn't proc on Mystic Shot (Q) even though the item describes the item to activate when a spell hits. 
2 Comments
Its actually working as intended, Ezreal's Q procs on hit effects (Red buff, Iceborn Gauntlet, etc) Since it does that, he does not gain the benefit of ludens on his q. E,W, and R will still proc it though