Board Thread:League of Legends discussion/@comment-24603390-20140317093853/@comment-1088372-20141026183555

"The equation can also be applied to abilities that scale with 100% AD"

What no it doesn't. You don't account for so many factors, but let's start with an easy one, base damage on skills.

deals 20/40/60/80/100 + 100% AD damage, while 60/95/130/165/200 + 80% bonus AD damage. Ignoring the difference in AD scaling, LW is better for Graves, because the higher base damage is also reduced by armor.

Let alone that you must assume some ability-to-autoattack-ratio, say 3 normal auto attacks every Gnar boomerang or something, but Caitlyn can stuff way more autoattacks inbetween two of her Peacemakers. The cooldown is also relevant in this, and the amount of damage abilities. A Riven can stuff you full of Q damage but it resets the aa timer every cast.

These examples assume no other form of armour penetration/reduction and 0% crit chance. How realistic.

They also assume the enemy's armor isn't increased by enemy champions, be they self- or allied-targeted buffs, like one of these. While you can say "just put the result number in the graph", you then have to estimate some ratio of "damage at buffed target"/"total damage on target".

has 100% AD scaling but deals magic damage, it benefits from AD but not from the penetration.

You can then calculate this for a single target, but for the whole item to be efficient you have to estimate the amount of damage at every different of the enemy champions, and even then it's not that simple. If getting AD instead of a LW would kill the adc faster but the tank slower, is that a bad thing? If you plan to only attack the tank, sure. But an adc taken out one second earlier could result in your teammate being alive. Then again, is anyone able to sufficiently damage the tankier enemies? Should you take on that role?

TL;DR: No, the calculation isn't that simple, graph is nearly useless. Yes, LW becomes better as the game continues, /copy "As a general rule, the higher your AD and the higher the targets armour the more efficient Last Whisper will be". Its efficiency is also greatly affected by which champ abilities you have, as well as your teammates and the enemy team. But most of all, it's a difference in playstyle; do you attack the high-armor characters more or the weak ones? Can you change that? Can the enemy force you not to?

TL;TL;DR: Dumbly buying LW as an "Xth" item is 'bad' no matter the X. But buying it too late hurts a lot more.