Hello guys,

At first excuse my poor English, I am not a native English speaker.


I would like to know if it is intersting to take the mastery"Weapon expertise" giving +10 prct of arm pen IF I DO NOT plan to take arm pen runes, or arm pen Item.
10 prct of 0 armpen means nothing right ??

This question may be stupid but I saw some guides proposing this mastery without item or rune of armpen.

Same question with acaneknowledge without magic pen ...

Thank you and sorry again for my English.

There is 2 kinds of penetration, Flat, and %. that mastery doesnt mean it increases your flat penetration (like from runes) but just straight up allows you to IGNORE 10% of any enemys armor. Flat armor penetration, such as from runes, ignores the flat amount of an enemys armor. If an enemy has 100 armor, and you take that talent with no runes or anything, they effectively only have 90 armor versus you. Yes its worth taking, always.

Just to add to that, all the Champions (I think) start of with a little Magic Resistence and Armour. So you won't get to a point where they start 0...

Like above, I think the Runes are all percentages, right?

I only use Magic and Armour Pen runes at the moment.

Percent-based armor penetration is based on your target's armor and has nothing to do with your flat armor penetration (the raw number). If you have 10% | 0 armor pen, you reduce 10% of the target's total armor. IF you have 10% | 8 armor pen, you remove 8 armor and then 10% of what's left.

^ Technically you remove the % last, but yes - it allows you to ignore a percentage of the enemy's armor, making it pretty darned powerful for a single mastery point.

thank you for yur answers guys :P