User blog comment:Centuriarch/Different ADC build./@comment-6301771-20140318032527

This "runaans is free crits" logical falacy needs to end. Right now. Teamwide DPS is only relevant in teamfights, and even then your job as an ADC isn't AOE damage. Your job is focusing down single targets and eleminating them before they get close to you. If you get straight AD and a Runaans you will lose every duel to every enemy ADC ever. You will be focused down and killed and then your "free crits" will be worth nothing.

Runaans is only good if you're a champion with innate on-hit effects. Varus, Kog'Maw, Teemo, maybe Jinx if it's super late game and you want to be able to push entire waves in a single shot. If you cannot abuse the fact that on-hit effects don't scale down, you should not be using Runaans. It does not give free crits. It makes your attacks a piddling nusance against 3 people as opposed to insta-gibbing them one at a time.