I could take the time and break it all down, but I would rather you just try it (standard game) and see what you think... Item build also works with Kog. Can switch out last item for BV, but I think the extra health/slow is enough once you get good, plus the slow is nice. If you can go without the Bloodthirster, I would use Tiamat (aoe slow/combos with explosive shot) to get "AOE CRAZY!!!" Use flash and Ghost to escape if you mess up!

206 Base Damage Per Hit
142 Magic Damage Per Hit (Based on 2000HP Target)
348 Base Damage Per Hit Total
15% Life Steal = +30HP Per Hit
@ 180% Increased Attack Rate Unbuffed (Rapid Fire add's an additional 90% Attack Rate over 7 Seconds)