First off, the stats aren't accurate, between the Tri-Force and the two Phantoms, your movement speed will be 430+ without boots. With the right runes and masteries, your attack speed will be 1.9+, and your life-steal with stacked bloodthirsters is 30-50%+.

This build gives Diana everything she needs to capitalize on the combination of her ult, and her passive, to kill quickly. She is quite strong as an AP, but if you can handle her, this AD build snowballs quite faster.