Item passive stacking

Item passive stacking describes the interactions between multiple items that have similar effects. The stacking of effects and items falls into different categories, and each category behaves differently.

Independent stacking

Effects stack independently if they stack additively. This is the simplest and most intuitive type of stacking: multiple effects or attributes will add to each other.

Example

Anti-Mage at level 25 with a Platemail has:

Armor = base armor + bonus armor = 14.2 + 10 = 24.2 armor

Effects that stack independently

• Bonus attack damage
• Bonus attributes (strength/agility/intelligence)
• Bonus mana/health (static amount)
• Bonus health regeneration/mana regeneration
• Bonus attack speed
• Bonus armor
• Lifesteal
• Mana Break (with the exception for Anti-Mage's mana break which does not stack with that of Diffusal Blade)
• Movement Speed bonuses from different categories (some items fall in the same category and therefore only the highest value applies, for example: Boots)
• Cleave damage (with the particularity that the damage from multiple instances of cleave is not actually added: each instance deals independent damage)
• Maim (which no longer exists)

Multiplicative stacking

Values that are stacked in a multiplicative manner have diminishing returns. The stacking effect can be calculated with the formula:

Total stack = 1 − ((1 − first instance) × (1 - second instance) × (1 - third instance) × ...) where each instance is a percentage.

Example:

Anti-Mage with level 4 Counterspell and a Cloak has a magic resistance of:

1 - (1 - 0.25) × (1 - 0.45) × (1 - 0.15) = 64.9375%

Effects that stack multiplicatively

• Magic Resistance
• Evasion
• Status Resistance

Limited stacking

These effects stack multiplicatively, but when two instances of the same effect happen at the same time, only the highest value is kept or the duration is refreshed.

Critical Strike

The highest crit multiplier has priority in case two critical strikes happen at the same time.

For example Tusk holding a Daedalus (230%) cannot crit when using Walrus PUNCH! (350%).

Damage block

Only one instance of damage block can proc at a time. The highest damage block value has priority.

Not stacking

Bash

The strength and damage components of multiple Skull Bashers and Abyssal Blades will independently stack, but the bash chance will not.

Chain Lightning

The attack speed and damage components of multiple Maelstroms and Mjollnirs will independently stack, but the chain lightning chance will not.

Auras

Auras provided by items do not stack with themselves, since they place a buff/debuff on the unit. Only the aura with the highest value will work.

Mechanics Stats Armor Attributes (Strength / Agility / Intelligence) Collision size Health (Health regeneration) Magic resistance Mana (Mana regeneration) Movement speed Status resistance Turn rate Vision Attack Attack animation Attack damage Attack modifier (Bash / Cleave & Splash / Critical strike / Lifesteal / Mana break) Attack range Attack speed Cast animation Cast range Damage types Motion buffer range Projectile speed Spell damage Spell lifesteal Abilities Abilities Aura Channeling Damage block Damage manipulation Damage over time Evasion Talents Teleport Status effects Attack immunity Break Cyclone Disable Disarm Ethereal Fear Forced movement Hex Hide Hypnosis Invisibility Invulnerability Leash Root Silence Sleep Slow Spell immunity Stun Taunt World Experience Gold Glyph of Fortification Map (Minimap) River Scan Runes Time of day Trees Gameplay Creep control techniques Denying Disjoint Dispel Ganking Harassment Hero complexity Initiating Item passive stacking Item sharing Jungling Lane Pushing Random distribution Roles Trap Units Ancient creeps Buildings Couriers Creep-heroes Heroes Illusions Lane creeps Neutral creeps Roshan Summons & Wards