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Magic Resistance
 
 
▶️ 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 Talent talents, certain items, and some abilities. The magic resistance of any unit can also be temporarily increased or reduced with some abilities.

Definition[]

Magic Resistance Mechanics Definition Examples
Base
  • Every hero innately has 25% base magic resistance.
  • Every 10 points of Intelligence attribute symbol 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 (Astral Spirit) icon Natural Order
Bonus
  • Magic resistance bonus or reduction sources from abilities, items, Talent talents, and other mechanics stack multiplicatively.
Rage icon Rage
Reductions Ancient Seal icon Ancient Seal
Ethereal
  • The magic resistance reduction of multiple ethereal sources does not stack, the one with higher value takes priority.
Decrepify icon 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:

Magic Resistance Total Magic Resistance = 1 - Magical Damage Multiplier

Magical Damage Multipler = [1 - Negation Multiplier × (0.25 + 0.001 × Intelligence attribute symbol)] × (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:


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[]

Spell Immunity icon

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
Can be used by illusions. Not disabled by Break.
Magic Resistance icon
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 attribute symbol 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[]

1 Requires Talent talent.
2a Requires Aghanim's Scepter icon Aghanim's Scepter.
2b Requires Aghanim's Shard icon Aghanim's Shard.

Creeps[]

Units Magic resistance
Alpha Wolf, Boar, Centaur Conqueror, Centaur Courser, Dark Troll Summoner, Fell Spirit, Forged Spirit, Ghost, Giant Wolf, Harpy Scout, Harpy Stormcrafter, Hellbear, Hellbear Smasher, Hill Troll, Hill Troll Berserker, Hill Troll Priest, Kobold, Kobold Foreman, Kobold Soldier, Mega Melee Creep, Mega Ranged Creep, Melee Creep, Minor Imp, Ogre Bruiser, Ogre Frostmage, Ranged Creep, Satyr Banisher, Satyr Mindstealer, Satyr Tormenter, Skeleton Warrior, Super Melee Creep, Super Ranged Creep, Treant, Vhoul Assassin, Wildwing, Wildwing Ripper 0%
Ancient Black Drake, Spiderite, Spiderling 25%
Ancient Black Dragon, Ancient Frostbitten Golem, Ancient Granite Golem, Ancient Ice Shaman, Ancient Rock Golem, Ancient Rumblehide, Ancient Thunderhide, Mud Golem, Shard Golem, Warpine Raider 30%
Eidolon, Hawk 30%/40%/50%/60%
Undying Zombie 33%
Flagbearer Creep, Mega Flagbearer Creep, Necronomicon Archer, Necronomicon Warrior, Super Flagbearer Creep 40%
Lycan Wolf 40%/50%/60%/70%
Wraith King Skeleton 50%
Roshan, Tormentor 55%
Lycan Lane Wolf 70%
Mega Siege Creep, Siege Creep, Super Siege Creep 80%

Summons[]

Summons Magic resistance
Astral Spirit, Earth, Fire, Mars Soldier, Spirit Bear 0%
Void 20%
Storm 25%
Warlock Golem 33%
Familiar 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 icon Natural Order (and Elder Titan Astral Spirit icon Astral Spirit's Natural Order (Astral Spirit) icon 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 icon Natural Order applies a base magic resistance negation multiplier of 0.6/0.4/0.2/0, reducing the base magic resistance down to 15%/10%/5%/0%.

Base Magic Resistance Negation Sources
  • Natural Order icon
    Radius: 350
    Base Magic Resistance Reduction: 40%/60%/80%/100%
    While Elder Titan Astral Spirit icon Astral Spirit is not summoned, the spirit is hidden and periodically moved along with Elder Titan, so that effectively, it is centered around him.
  • Natural Order (Astral Spirit) icon
    Radius: 350
    Base Magic Resistance Reduction: 40%/60%/80%/100%
    The effects are provided by an aura, affects enemies within range of the Elder Titan Astral Spirit icon Astral Spirit. The reduction is based on the enemies' base magic resistance. The debuff lingers for 1 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 icon 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[]

1 Requires Talent talent.
2a Requires Aghanim's Scepter icon Aghanim's Scepter.
2b Requires Aghanim's Shard icon 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.

1 Requires Talent talent.
2a Requires Aghanim's Scepter icon Aghanim's Scepter.
2b Requires Aghanim's Shard icon Aghanim's Shard.

Talents[]

Magic Resistance
Talent icon
Ability
Passive
Affects
Self
There is no description for this ability.
Magic Resistance Bonus: Varies

  • 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 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
  • Death Prophet minimap icon +12%
  • Morphling minimap icon +15%
  • Techies minimap icon +20%
  • Timbersaw minimap icon +20%
  • Muerta minimap icon +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%)
Enchantress minimap icon +8% 31% +6%
Death Prophet minimap icon +12% 34% +9%
Morphling minimap icon +15% 36.25% +11.25%
Techies minimap icon Timbersaw minimap icon +20% 40% +15%
Muerta minimap icon +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

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 icon Arcanist's Armor 20 N/A N/A
Cloak icon Cloak 20 800 Gold 40 Gold
Cloak of Flames icon Cloak of Flames 10 N/A N/A
Eternal Shroud icon Eternal Shroud 25 3600 Gold 144 Gold
Glimmer Cape icon Glimmer Cape 25 2150 Gold 86 Gold
Mage Slayer icon Mage Slayer 20 2825 Gold 141.25 Gold
Martyr's Plate icon Martyr's Plate 25 N/A N/A
Occult Bracelet icon Occult Bracelet 5 N/A N/A
Pipe of Insight icon Pipe of Insight 20 3725 Gold 186.25 Gold
Trickster Cloak icon Trickster Cloak 17 N/A N/A
Unwavering Condition icon Unwavering Condition 95 N/A N/A
Vambrace (Strength) icon Vambrace (Strength) 8 N/A N/A
Values do not include portions from actives or auras.


Reducing Sources[]

1 Requires Talent talent.
2a Requires Aghanim's Scepter icon Aghanim's Scepter.
2b Requires Aghanim's Shard icon 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)

1 Requires Talent talent.
2a Requires Aghanim's Scepter icon Aghanim's Scepter.
2b Requires Aghanim's Shard icon Aghanim's Shard.

Illusions Negation[]

Main Article: Illusions

Illusions
Not disabled by Break.
Illusion icon
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.
Attack Damage Against Reinforced: Outgoing Damage Manipulation 0.4
Bonus Attack Damage Negation: 100%
Bonus Armor Negation: 100%
Bonus Magic Resistance Negation: 100%
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 icon 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 icon 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:

Magic Resistance Total Magic Resistance = 1 - Final Magic Damage Multiplier

Final Magic Damage Multiplier = (Magic Damage Multiplieri )

For base magic resistance, Magic Damage MultiplierBase = [1 - Negation Multiplier × (0.25 + 0.001 × Intelligence attribute symbol)]
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 × Intelligence attribute symbol)] × (1 - Magic Resistance Modifiers i )

Example 1
Magic Resistance Bonus and Magical Damage Multiplier
Anti-Mage minimap icon Anti-Mage with level 4 Counterspell icon Counterspell and has a Mage Slayer icon Mage Slayer equipped. Without factoring in the base magic resistance increase by Intelligence attribute symbol intelligence, what is his current magic resistance?
Base hero magic resistance: 0.25
Bonus magic resistance: Counterspell icon Counterspell: 0.45, Mage Slayer icon Mage Slayer: 0.2
Final Magic Damage Multiplier
= (1 - 0.25) * (1 - 0.45) * (1 - 0.2)
= 0.33
All incoming magical damage dealt to Anti-Mage minimap icon Anti-Mage will now be multiplied by 0.33. His current total Magic Resistance magic resistance in this example is 1 - 0.33 = 67%.
Example 2
Magic Resistance Reduction and Magical Damage Multiplier
Marci minimap icon Marci is now affected by two magic resistance reduction sources, level 4 Ancient Seal icon Ancient Seal, a level 4 Decrepify icon Decrepify and Nihilism icon Nihilism.
Without factoring in the base magic resistance increase by Intelligence attribute symbol intelligence, what is her current magic resistance?
Base hero magic resistance: 0.25
Magic resistance reduction: Ancient Seal icon Ancient Seal: -0.35, Decrepify icon Decrepify: -0.6, Nihilism icon Nihilism -0.3
Final Magic Damage Multiplier
= (1 - 0.25) * (1 - -0.35) * (1 - -0.6)
= 1.62
All incoming magical damage dealt to Marci minimap icon Marci will now be multiplied by 1.62. Her current total Magic Resistance magic resistance in this example is 1 - 1.62 = -62%.
The ethereal magic resistance reduction is not factored into the calculations because Decrepify icon Decrepify has a higher magic resistance reduction value than Nihilism icon 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 = CurrentHP / Final Magic Damage Multiplier

Example 1
Marci minimap icon Marci is Level 6 and has a 922 health, what is her EHP against magical damage?
Base magic resistance: 0.278
EHPmagic
= 922 / 0.722
= 1277.01
Marci minimap icon Marci has 1277.01 EHP against magical damage in this example.
Example 2
Marci minimap icon Marci from Example 1 now is affected by two magic resistance reduction sources, a level 4 Ancient Seal icon Ancient Seal and level 4 Decrepify icon Decrepify. What is her EHP against magical damage now?
Health: 922
Base magic resistance: 0.278
Magic resistance reduction: Ancient Seal icon Ancient Seal: -0.35, Decrepify icon Decrepify: -0.6
Final Magic Damage Multiplier
= (1 - 0.278) * (1 - -0.35) * (1 - -0.6)
= 1.55952
EHPmagic
= 922 / 1.55952
= 591
Marci minimap icon Marci has 591 EHP against magical damage in this example.

Recent Changes[]

Version
Description
  • 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 attribute symbol Intelligence now grants 0.1% Base Magic Resistance per point



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