AP: 539
Magic penetration (in %): 41%;
Magic penetration: 48 (if passive inactive: 38) (to understand how Magic penetration works see the last chapter)
Health: 2530
Mana: 2313
Movement speed: 406

I think that blue Fiddlesticks is here for 2 main reasons:

• Crowstorm in teamfights
• Reap each time you can

I like to play this way with fiddle because it is very funny and with these items you become very useful for your team, furthermore Rylai's Crystal Scepter's passive helps you and your team:

• Ennemies slowed in your Crowstorm, so they are more likely to stay inside it
• Liandry's Torment's passive makes double damage
• Bountiful Harvest slow automatically, so you can keep Terrify for another situation and the target takes more time to get out of your Bountiful Harvest range
• Your 400/500 (per hit) Reap slow your enemies by 35%, so they can't get far away from each other and the crow will bounce on them

With Liandry's Torment your Reap is VERY annoying for the enemies and your Crowstorm deals much more damage

Furthermore these two items give you 150 AP (not that much for 2 items) and 700 HP (that you are very likely to need because Fiddlesticks is very squishy)

If you want to make the combo Liandry's Torment + Rylai's Crystal Scepter, you will have to chose between Rabadon's Deathcap and Void Staff. By reading the next chapter you can calculate that with Rabadon's Deathcap you will deal more damage than with Void Staff if your enemies have less than 55 magic resist. After 55 magic resist it's the opposite.

When you deal magic damage to an enemy unit there is a factor that reduces (in most of the cases) the amount of damage: it is the magic resist.

First of all let's see how magic resist works: a Lux, that has 0 magic penetration, sends her ultimate ( Final sparks) that does 500 magic damage. She hits Talon that has 30 magic resist and 500 HP. The damage dealt to Talon is equal to: (damage of attack)*(100)/(100 + magic resist), (formula taken from LOL wiki). You can see magic resist a factor (< 1) that multiplies the magic damage, and the more the MR is high, the lower is the factor. This factor is 100/(100 + magic resist). So in this case Lux deals 500*100/(100+30) = 385 of damage, Talon has 115 HP left.

To make it simpler think that

• 0 magic resist = 100% of damage
• 50 magic resist = 2/3 of damage
• 100 magic resist = half of damage
• 200 magic resist = 1/3 of damage

This is only true you have 0 magic penetration.


But the magic resist used in the formula is not the one of the champion that is receiving the damage, but it is a number that takes into account the magic penetration of the attacker and the magic resist of the defender. In the case of Talon, Lux had no magic penetration so this number (that we will call X, from now on) is equal to the magic resistance of Talon.
The magic penetration in % is an ignore of a % of magic resist.
The other magic penetration (the one that is not in %) reduces directly the magic resist.
The one in % applies before the other one.
So if we have 15 magic penetration and ignore 35% of magic resistance ( Void Staff), and the enemy has 40 magic resist, X = 40*(1-0.35) - 15 = 11
For A magic penetration, B magic penetration (in %) and M magic resistance of the enemy, X = [M*(1-(B/100))]-A

And if we call D the statistic damage (the one written on the ability when you hover it) the complete formula is D*(100)/(100+[M*(1-(B/100))]-A)

And this X can be negative! So that the factor becomes greater than 1, and you deal more damage than what is written in the ability!

It is the case of this build: let's say that you send Reap ( Fiddlesticks) on someone that has 30 MR (a normal ADC has 35), (here D = 390, A=48, B=41, M= 30), X = 30*(1-(41/100))-48 = -30 and dmg dealt = 390*(100)/(100+[30*(1-(41/100))]-48) = 560, if your target has 100 MR, then X=11 and the damage dealt is 350.