General Guide by Complexicate

Introduction

This is a summary of some of the most important formulas that League of Legends uses, and the things that affect those formulas.

It was originally started because I kept playing with builds that focused on one stat or another. The rune calculations and the item numbers make it a quick and easy reference for that.

Attack Speed

How it works
Cap = 2.500 attacks per second

Attack Speed = Base Attack Speed * (100% + Bonus Percent)

Base Attack Speed
Every champion's "base attack speed" is calculated using a hidden variable called "attack delay".
Base Attack Speed = 0.625 / (1 + attack_delay)

Attack Delay (Approximate Base Attack Speed)
-0.10 (0.69444):
-0.09 (0.68681):
-0.08 (0.67935):
-0.07 (0.67204):
-0.06 (0.66489):
-0.05 (0.65789):
-0.04 (0.65104):
-0.03 (0.64433):
-0.02 (0.63776):
+0.00 (0.62500):
+0.02 (0.61275):
+0.08 (0.57870):


Bonus Attack Speed Percent
Bonuses are additive
25 + 30 = 55% bonus

If a champion has about 0.665 base attack speed, 376% faster is 2.500
That means that 276% bonus would reach the 2.500 cap.


Bonus attack speed comes from 5 sources

1. Runes
2. 1 Mastery
3. Items
4. Every level, bonus attack speed is added (between 1% to 4% depending on the champion).
5. Some champion abilities
   , etc.

Greater Quintessence of Attack Speed

Greater Mark of Attack Speed

Greater Seal of Attack Speed

Greater Glyph of Attack Speed

Critical Strike Chance

How it works
Cap = 100%

Crit Percents are additive
25 + 30 + 30 = 85% chance


Critical Strike Chance comes from 3 sources

1. Runes
2. Items
3. 3 champion abilities:
   Ashe's Focus
   Pantheon's Heartseeker Strike
   Tryndamere's Battle Fury

Greater Quintessence of Critical Chance

Greater Mark of Critical Chance

Greater Seal of Critical Chance

Greater Glyph of Critical Chance

Cooldown Reduction

How it works
Cap = 40%

CDR is additive
4% "Sorcery" Mastery + 6% "Intellegence" Mastery + 15 = 25% CDR


CDR comes from 4 sources

1. Runes
2. 3 Masteries
3. Items
4. 4 champion abilities:
   Heimerdinger's UPGRADE!!!
   Ryze's Overload
   Twisted Fate's Stacked Deck
   Viktor's Augment: Gravity

1. "Focus" runes are more powerful than "Celerity" until level 13 and the first 12 levels often set the balance of the game.
2. At level 18, Celerity x3 only gives 2.1% more CDR than Focus x3, and Celerity x9 only gives 2.77% more CDR than Focus x9. Most people do not think this late game CDR is worth giving up the early game CDR.

• -15.64% from x3 + x9
• -10% from Masteries (9/0/21)
• -15% from just one item

Greater Quintessence of Cooldown Reduction

Greater Glyph of Cooldown Reduction

Greater Seal of Cooldown Reduction

Greater Mark of Cooldown Reduction

Celerity runes only come as Quintessences or Glyphs .

Note: Testing on a rune page, I found that the Greater Glyph of Scaling Cooldown Reduction is actually closer to -0.9576% at 18 (-0.0532% per level). It has been rounded for the tooltip.

Greater Quintessence of Scaling Cooldown Reduction

Greater Glyph of Scaling Cooldown Reduction

Greater Quintessence of Scaling Cooldown Reduction

Greater Glyph of Scaling Cooldown Reduction

Greater Quintessence of Scaling Cooldown Reduction

Greater Glyph of Scaling Cooldown Reduction

Greater Quintessence of Scaling Cooldown Reduction

Greater Glyph of Scaling Cooldown Reduction

Armor and Magic Resistance

How they work
Armor lets only a fraction of physical damage through.
Magic Resistance lets only a fraction of magic damage through.

That fraction is calculated the same way for both Armor and Magic resistance.
Physical Damage is multiplied by the fraction: 100 / (100 + Armor)
Magic Damage is multiplied by the fraction: 100 / (100 + MR)

If you are hit by 600 magic damage and have 50 MR, it will only hurt for 400 damage.
600 * 100/(100 + 50) = 600 * 2/3 = 400


Fractions of damage
Your protection -> Damage you take
50 -> 2/3 damage
100 -> 1/2 damage
200 -> 1/3 damage
300 -> 1/4 damage

Adding more and more protection gets less and less cost effective.
The first 50 points (from 0 to 50) block 1/3 (33%) of incoming damage.
The next 50 points (from 50 to 100) block 1/6 (17%) of incoming damage.
The next 50 points (from 100 to 150) block 1/10 (10%) of incoming damage.
The next 50 points (from 150 to 200) block 1/15 (6%) of incoming damage.




See:
Magic Resistance on LoL Wiki
Armor on LoL Wiki

Resistance Reduction

The Armor and MR from the chapter above can be lowered 2 different ways.

1. Reduction: can put resistances below 0, granting extra damage.
2. Penetration: does nothing when resistance is below 0.

1. Percentage Reduction
2. Flat Reduction
3. Flat Penetration
4. Percentage Penetration

1. Items
2. Champion Abilities

1. Runes
2. Masteries
3. Items

Greater Quintessence of Magic Penetration

Greater Mark of Magic Penetration

Greater Glyph of Magic Penetration

Greater Quintessence of Hybrid Penetration

Greater Mark of Hybrid Penetration