Diana build options
Diana's passive at level 18 does 250 damage plus 80% of AP every third attack. This does more damage than any other ability. I see a lot of people build her like katarina. Tons of AP and abyssal/sorc shoes, but wouldn't it be better to build diana around her passive?
AS, on hit items, some crit. Why isn't
considered? Her passive can crit and apply on hit effects, so
would synergize with PD. With over 2.0 AS, those 5 stacks come quick. Add an
to the mix, with sorc shoes and you melt anyone not stacking MR.
+ 
I haven't done the math on any of this, just playing around with some builds. Anything along these lines seem viable?

if you don't have full cdr from runes (I personally like to use per lvl cdr glyphs so I can get the full 40% off of that, nashor's, and the mastery)
if you don't.

until late game, when if the situation dictates you can replace it with the Luden's.