User blog comment:Fistful of Force/How to beat Diana in lane./@comment-5194571-20120818140302/@comment-4834593-20120818222527

Play safe until level 5 (when you have rank 3 E). Then start E harras from as far back as you possibly can.

I've noticed this earlier too - Sometimes, harras costs too much mana, but from the point of that you have rank 3 in it, it becomes worth it.

Also don't forget to buy the red augment and a Chalice of Harmony. Mostly the Chalice. Whenever you face her while playing someone with mana, rush Chalice.