Magic Resistance

• Magic Resistance
• Changelogs

“

Thy magic harms me not. — Anti-Mage

”

Magic Resistance is a stat that reduces (or increases, if negative) a percentage of magical damage a unit takes from spells and magic attacks. Every unit is capable of gaining or losing magic resistance, and most units start with a small amount of base magic resistance. A hero's magic resistance can be passively increased with talents, certain items, and some abilities. The magic resistance of any unit can also be temporarily increased or reduced with some abilities.

Definition

Mechanics	Definition	Examples
Base	Every hero innately has 25% base magic resistance. Every 10 points of intelligence additionally grants 1% base magic resistance.
Negation	A multiplier applied that affects and reduces the unit's base magic resistance. Other magic resistance bonus sources are not affected.	Natural Order
Bonus	Magic resistance bonus or reduction sources from abilities, items, talents, and other mechanics stack multiplicatively.	Rage
Reductions		Ancient Seal
Ethereal	The magic resistance reduction of multiple ethereal sources does not stack, the one with higher value takes priority.	Decrepify

For illusions, all Magic Resistance Modifiying sources will be set to 0, since illusion do not benefit form magic resistance bonus.

The magical damage multiplier is applied to all incoming magical damage sources to calculate the total magic damage received, after being reduced by damage barrier sources.

Equations

The total magic resistance displayed on the HUD and the incoming magical damage multiplier can be defined as:

Total Magic Resistance = 1 - Magical Damage Multiplier

Magical Damage Multipler = [1 - Negation Multiplier × (0.25 + 0.001 × )] × <math>\prod_{i=1}^{n}</math>(1 - Magic Resistance Modifiers _i )

Actual Magic Damage Received

The total or actual magic damage dealt is equal to how much health a target immediately loses as a direct result. The incoming damage received is calculated by the following factors, listed in the order of their applications:

• Actual Magical Damage Received
  • Total Magical Damage
  • - Magic Damage Block
  • × Magic Resistance Multiplier
  • - Magic Damage Barrier
  • × Other generic incoming damage manipulation Sources

In equation form:

Actual Magical Damage Received = [ (Total Magical Damage - Magic Damage Block) × Magic Resistance Multiplier - Magic Damage Barrier] × Other generic incoming damage manipulation Sources

The Total Magical Damage can be amplified by the damage dealer's generic outgoing damage manipulation (e.g. spell amplification) before other calculations are performed.

Damage Block

Main Article: Damage Block

Damage Barrier

Main Article: Damage Barrier

Spell Immunity

File:Spell Immunity icon.png

Default buff icon
▶️ Error sound.

Main Article: Spell Immunity

Spell Immunity (formerly known as magic immunity) is a status that prevents most abilities from targeting the affected unit. This includes a single-targeted, area of effect, passive and active abilities. A unit having 100% magic resistance neither equals being spell immune nor debuff immune. Therefore, all three of these mechanics are separate and different mechanics.

The biggest difference with Magic Resistance is that Spell Immune units do not interact with spell damage at all, while magic resistance reduces incoming magical damage from abilities.

Spell immunity usually are granted to some units as an extra layer of protection, usually on ward-type units, or in combination with invulnerability.

Base Magic Resistance

Base magic resistance consists of one fixed value set for each unit individually, and it can be a negative number.

Heroes

Main Article: Intelligence

Base

128x128px

Ability
Passive

Affects
Self

All heroes currently have 25% base magic resistance.

Base Magic Resistance: 25%

Base Magic Resistance Bonus per Intelligence: 0.1%

NOTES

• For heroes, per point of intelligence grants 0.1% base magic resistance bonus, which is gained by leveling up, acquiring certain items, or with the help of certain abilities.

Base Increasing Sources

Base Magic Resistance Increasing Sources

• Attributes – Attribute Bonus
• Alchemist – Aghanim's Scepter Synth
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• Invoker – Exort
• Power Treads – Switch Attribute
• Magnus – Reverse Polarity¹
• Silencer – Glaives of Wisdom
• Skywrath Mage – Shield of the Scion
• Vambrace – Switch Attribute
• Morphling – Morph^2a

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Creeps

Unit	Magic Resistance
Ghost, Minor Imp, Kobold, Kobold Soldier, Kobold Foreman, Hill Troll Berserker, Hill Troll Priest, Vhoul Assassin, Fell Spirit, Harpy Scout, Harpy Stormcrafter, Centaur Courser, Centaur Conqueror, Giant Wolf, Alpha Wolf, Satyr Banisher, Satyr Mindstealer, Ogre Bruiser, Ogre Frostmage, Satyr Tormenter, Hellbear, Hellbear Smasher, Wildwing, Wildwing Ripper, Hill Troll, Dark Troll Summoner, Skeleton Warrior, Boar, Treant, Forged Spirit	0
Ancient Black Drake, Spiderling, Spiderite	0.25
Warpine Raider, Ancient Frostbitten Golem, Ancient Ice Shaman, Mud Golem, Ancient Black Dragon, Ancient Rock Golem, Ancient Granite Golem, Ancient Rumblehide, Ancient Thunderhide, Shard Golem	0.3
Hawk, Eidolon	0.3/0.4/0.5/0.6
Undying Zombie	0.33
Necronomicon Warrior, Necronomicon Archer	0.4
Lycan Wolf	0.4/0.5/0.6/0.7
Wraith King Skeleton	0.5
Tormentor, Roshan	0.55

Summons

Unit	Magic Resistance
Earth, Astral Spirit, Mars Soldier, Fire, Spirit Bear	0
Void	0.2
Storm	0.25
Warlock Golem	0.33
Familiar	0.35

Base Magic Resistance Negation

Some abilities negate or ignore a unit's base magic resistance by removing a percentage of the base magic resistance on the target. This magic resistance negation only affects the base magic resistance value of units, other magic resistance bonus sources are not affected.

Natural Order (and Astral Spirit's Natural Order) interact with magic resistance differently. Instead of stacking multiplicatively with other sources of magic resistance, it acts as a multiplier for the base magic resistance. These two abilities are currently the only two sources of base magic resistance negation, and it is defined as

This means, for heroes with 25% base magic resistance, Natural Order applies a base magic resistance negation multiplier of 0, reducing the base magic resistance down to 0%.

Base Magic Resistance Negation Sources

• Elder_Titan - Natural Order
  
  Radius: 350
  Base Magic Resistance Reduction: 1
  While Astral Spirit is not summoned, the spirit is hidden and periodically moved along with Elder Titan, so that effectively, it is centered around him.
• Astral_Spirit - Natural Order
  
  Radius: 350
  Base Magic Resistance Reduction: 1
  The effects are provided by an aura, affects enemies within range of the Astral Spirit. The reduction is based on the enemies' base magic resistance. The debuff lingers for second.

Pure Damage

Main Articles: Damage Types and HP Removal

Pure Damage is a damage type that is not reduced by Armor or Magic Resistance. It is also not amplified by magical damage amplification abilities, fully ignores Armor and Damage Block. It does not affect invulnerable units.

There are a few sources that can manipulate Pure Damage, with Dispersion being one of them. This mechanic is called damage reduction. Pure damage affects units with Spell Immunity (because spell immunity does not block damage), but that does not mean that an ability that deals pure damage is able to target spell immune units.

Modifying Magic Resistance

Several abilities and items have abilities that grant or reduce magic resistance.

Increasing Sources

Magic Resistance Increasing Sources

• Anti-Mage – Counterspell
• Arc Warden – Magnetic Field (Radiant)^2b
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• Brewmaster – Drunken Brawler Earth Stance
• Centaur Courser – Cloak Aura
• Doom – Devour¹
• Dragon Knight – Black Dragon Form^2a
• Huskar – Berserker's Blood
• Lina – Flame Cloak
• Lone Druid – Demolish
• Spirit Bear – Demolish
• Meepo – Divided We Stand
• Oracle – Fate's Edict
• Pipe of Insight – Insight Aura
• Vambrace – Switch Attribute
• Viper – Corrosive Skin

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Debuff Immunity

Main Article: Debuff Immunity

Debuff Immunity stops most effects of debuffs' effects on a unit without dispelling the debuffs while granting magic resistance bonus as an effect. The following abilities grant debuff immunity and magic resistance bonus.

Debuff Immunity Sources

• Black King Bar – Avatar
• Clockwerk – Power Cogs¹
• Dawnbreaker – Starbreaker^2b
• Earth – Debuff Immunity
• Elder Titan – Astral Spirit^2b
• Grimstroke – Dark Portrait
• Huskar – Life Break
• Juggernaut – Blade Fury
• Legion Commander – Press the Attack¹
• Lifestealer – Rage
• Lion – Mana Drain^2b
• Omniknight – Repel
• Pangolier – Roll Up
• Pangolier – Rolling Thunder

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Talents

Magic Resistance

Ability
Passive

Affects
Self

There is no description for this ability.

Magic Resistance Bonus: Varies

NOTES

 

5935, 5994, 5936, 5937, 6299, 1089, 6138, 6000, 6091, 6221, 6386, 6663, 6641, 6965, 6874

special_bonus_magic_resistance_5/6/8/10/12/14/15/20/25/30/35/40/50/80/100

• Increases the hero's magic resistance.

• Stacks multiplicatively with other sources of magic resistance.

• The following values exist:
  • 5%/6%/8%/10%/12%/14%/15%/20%/25%/30%/35%/40%/50%/80%/100%

The following heroes have a talent that grants them bonus magic resistance.

Bonus	Level 10		Level 15		Level 20		Level 25
	Left	Right	Left	Right	Left	Right	Left	Right
Magic Resistance	+12%	+15% +20%				+20%	+25%

With the 25% magic resistance and no other sources of magic resistance, the following heroes with bonus magic resistance talents effectively have their magic resistance increased up to:

Heroes	Magic Resistance Talent	Magic Resistance Total	Increased Value
	Basic Magic Resistance (25%)
	+8%	31%	+6%
	+12%	34%	+9%
	+15%	36.25%	+11.25%
	+20%	40%	+15%
	+25%	43.75%	+18.75%

Besides these, the following heroes have talents that increase the magic resistance of the units they summon

Specific Summons Magic Resistance Bonus

• Warlock - Talent by Level 25 Left
  
  +80% Warlock Golem Magic Resist:
  Increases the unit's total magic resistance to 87%.

Items

These items grant bonus percentage-based magic resistance values to the hero who has them equipped.

Magic Resistance Granting Items

Item	Value	Item Cost	Cost/Value Point
Arcanist's Armor	20%	N/A	N/A
Cloak	20%	800	40
Cloak of Flames	10%	N/A	N/A
Eternal Shroud	20%	3700	185
Glimmer Cape	25%	2150	86
Mage Slayer	20%	2200	110
Martyr's Plate	25%	N/A	N/A
Occult Bracelet	5%	N/A	N/A
Pipe of Insight	20%	3725	186.25
Trickster Cloak	17%	N/A	N/A
Unwavering Condition	95%	N/A	N/A
Vambrace (Strength)	8%	N/A	N/A
Values do not include portions from actives or auras.

Reducing Sources

Magic Resistance Reducing Sources

• Ancient Apparition – Ice Vortex
• Ceremonial Robe – Ceremonial Aura
• Grove Bow – Magic Amp
• Keeper of the Light – Solar Bind
• Skywrath Mage – Ancient Seal
• Shadow Fiend – Requiem of Souls
• Techies – Proximity Mines
• Viper – Poison Attack

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Ethereal

Main Article: Ethereal

Ethereal, sometimes referred to as ghost form, is a type of status effect that makes affected units immune to all physical damage, grants them attack immunity, while also disarming them. It also usually - but not always - reduces their magic resistance, causing them to take additional magical damage. Affected units are able to control every other aspect of their character.

The magic resistance reduction of multiple ethereal effects does not stack, the one with a higher value takes priority, and it is defined as:

Ethereal Magic Resistance Reduction = (1 + MAX Ethereal Magic Resistance Reduction)

Ethereal Sources

• Ethereal Blade – Ether Blast
• Ghost Scepter – Ghost Form
• Leshrac – Nihilism
• Muerta – Pierce the Veil
• Necrophos – Ghost Shroud
• Pugna – Decrepify

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Illusions Negation

Main Article: Illusions

Illusions

Ability
Innate

Affects
Self

This unit is an illusion. Its stats, level, ability levels, and items are all set upon creation and do not adapt to the original hero.

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Bonus Attack Damage Negation: 100%

Bonus Armor Negation: 100%

Bonus Magic Resistance Negation: 100%

Modifiers [?]

modifier_property_bonusdamageoutgoing_percentage

Undispellable

modifier_property_damageoutgoing_percentage_illusion_amplify

Undispellable

NOTES

• Bonus magic resistance negation only affects the bonus magic resistance value of illusions, their base magic resistance is unaffected and still can be manipulated by other base magic resistance negation sources normally.

Stacking

Each source of magic resistance acts as a incoming magic damage multiplier that work independently from each other.

• For example, source that "increase magic resistance by 30%" or simply states "+30% Magic resistance" means that it acts as a 1 - 0.3 = 0.7 incoming magic damage multiplier.
• They work independently from each other, meaning apply multiple magic resistance effects is equivalent to apply their corresponding magic damage multiplier in a multiplicative manner. This is similar to how evasion effects stack.
  • A unit that has a +30% Magic resistance and another +40% Magic resistance means that it has a 0.7 * 0.6 = 0.42 incoming magic damage multiplier. It will only take 42 damage when a 100 magic damage instance is dealt to it.
  • Activating Black King Bar will reduce the magic damage a hero is taking by half, regardless of how much magic resistance it has.
  • In other direction, a unit that has a -40% Magic resistance and another -60% Magic resistance means that it has a 1.4 * 1.6 = 2.24 incoming magic damage multiplier.

Because of this, combination of multiple magic resistance sources that are individually less than 100% is also effectively less than 100%.

• Fate's Edict grants 100% magic resistance, which acts as a 0 incoming magic damage multiplier. When it stacks with other magic resistance sources, the final incoming magic damage multiplier is always 0 (due to multiplication with 0). Thus, the affected unit will always take 0 magic damage, no matter what other source of negative magic resistance it has.

The magic resistance displayed in HUD is calculated from the final multiplier, after all magic resistance effects is accounted for.

• A unit with a 2.24 incoming magic damage multiplier will be displayed as having -124% magic resistance.

The total magic resistance displayed on the HUD and the incoming magical damage multiplier can be defined as:

Total Magic Resistance = 1 - Final Magic Damage Multiplier

Final Magic Damage Multiplier = <math>\prod_{i=1}^{n}</math>(Magic Damage Multiplieri )

For base magic resistance, Magic Damage MultiplierBase = [1 - Negation Multiplier × (0.25 + 0.001 × )]

For other magic resistance sources, Magic Damage Multiplieri = 1 - Magic Resistance

In full equation,

Total Magic Resistance = 1 - [1 - Negation Multiplier × (0.25 + 0.001 × )] × <math>\prod_{i=1}^{n}</math>(1 - Magic Resistance Modifiers i )

Example 1

Magic Resistance Bonus and Magical Damage Multiplier

Anti-Mage with level 4 Counterspell and has a Mage Slayer equipped. Without factoring in the base magic resistance increase by intelligence, what is his current magic resistance?

Base hero magic resistance: 0.25

Bonus magic resistance: Counterspell: , Mage Slayer: 0.2

Final Magic Damage Multiplier

= (1 - 0.25) * (1 - ) * (1 - 0.2)

=

All incoming magical damage dealt to Anti-Mage will now be multiplied by . His current total magic resistance in this example is 1 - = %.

Example 2

Magic Resistance Reduction and Magical Damage Multiplier

Marci is now affected by two magic resistance reduction sources, level 4 Ancient Seal, a level 4 Decrepify and Nihilism.

Without factoring in the base magic resistance increase by intelligence, what is her current magic resistance?

Base hero magic resistance: 0.25

Magic resistance reduction: Ancient Seal: -, Decrepify: -, Nihilism -0.3

Final Magic Damage Multiplier

= (1 - 0.25) * (1 - -) * (1 - -)

=

All incoming magical damage dealt to Marci will now be multiplied by . Her current total magic resistance in this example is 1 - = %.

The ethereal magic resistance reduction is not factored into the calculations because Decrepify has a higher magic resistance reduction value than Nihilism.

Effective Health

The total amount of magic damage a unit can take due to magic resistance is known as Effective HP (or EHP). Despite each source of magic resistance increasing the magic resistance value less the higher it is and making them seem less effective, each source increases the unit's effective HP against magic damage by their base value.

A unit with 0% magic resistance has 100% effective HP against magical damage, which means magical damage equaling 100% of its health is required to kill it. All heroes have 25% magic resistance by default, making their effective HP against magical damage 133.33%.

Magic Resistance	-100%	-75%	-50%	-25%	0%	25%	50%	75%	100%
Effective HP	500	571	667	800	1000	1333	2000	4000	∞

This definition of EHP assumes all damage taken is magic damage. EHP against physical damage (e.g. basic hero attacks etc.) is modified by armor.

Effective HP against magical damage is defined as

EHP = Current_HP / Final Magic Damage Multiplier

Example 1

Marci is Level 6 and has a 1022 health, what is her EHP against magical damage?

Base magic resistance: 0.278

EHP_magic

= 1022 / 0.722

= 1415.51

Marci has 1415.51 EHP against magical damage in this example.

Example 2

Marci from Example 1 now is affected by two magic resistance reduction sources, a level 4 Ancient Seal and level 4 Decrepify. What is her EHP against magical damage now?

Health: 1022

Base magic resistance: 0.278

Magic resistance reduction: Ancient Seal: -, Decrepify: -

Final Magic Damage Multiplier

= (1 - 0.278) * (1 - -) * (1 - -)

=

EHP_magic

= 1022 /

=

Marci has EHP against magical damage in this example.

Recent Changes

Main Article: Magic Resistance/Changelogs

Version

Description

7.33
(2023-04-20)

• ADDED new Debuff Immunity mechanic.
  • Debuff Immunity stops most effects of debuffs' effects on a unit without dispelling the debuffs while granting magic resistance bonus as an effect.
• Magical Damage Barrier Magical Damage Barrier
  • Now stacks additively with the same damage-type barrier sources, and independently with other damage-type barrier sources.
  • Now absorb damage calculated before all magic resistance reductions.
• Intelligence now grants 0.1% Base Magic Resistance per point

7.07
(2017-10-31)

• Fixed magic damage sources from attacks not being blocked by magic damage barrier type abilities (i.e. Lua error in Module:Ability_ID at line 31: Could not find Lpdb data for "Barrier" on "Hood of Defiance". , Flame Guard etc.).

6.52
(0000-01-01)

• Fixed Phantom Edge not stacking with other magic resistance sources.