Originally Posted by Ganciel Dren
all right i'm a little confused here . so please correct me if i'm wrong .
target has 100
i have 29 armor pen from runes
and i usually get last whisper and black cleaver .
-armor reduction: 100-60 (5 stacks from cleaver) = 40 armor
-% armor penetration: 40 * .6 = 24
-flat armor penetration: 24 - 29 = -5 armor
so wouldn't it still be good to combine last whisper and black cleaver ?
Nein, my good sir. Only reduction can take armor to the negative, penetration stops at zero. If you're going to buy Last Whisper, please ignore Black Cleaver and instead buy Bloodthirster or Infinity Edge. Due to the fact that reduction is applied first, Last Whisper effectively makes 40% of your reduction redundant.
Also, at Def Exe: On Shaco, your priorities are Damage, Crit Damage, and Armor Penetration. You generally assume that you hit the target at most twice. Backstab deceive, a second attack, and a shiv to seal the deal. If you have failed to seal the deal with this, you probably just died. Last Whisper is better because 40% armor penetration immediately beats out 12 after each attack applies. Also, please throw out that Phantom Dancer and replace it with an item that actually helps Shaco, like Bloodthirster (which btw is also a better use of your second BF sword than Black Cleaver due to having 25 more damage).
Also, as to armor: A character with no armor items has ~70-80 armor at level 18. An armor-stacker like Rammus might easily break 400, considering Frozen Heart, Warden's Mail, Guardian Angel, and Thornmail are all made with both a Chain Vest and a Cloth Armor (and thus have armors between 80 and 100) and he has a passive massive increase to armor when his Defense curl is on.