“ | ▶️ 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 |
|
|
Negation |
|
Natural Order |
Bonus |
|
Rage |
Reductions | Ancient Seal | |
Ethereal |
|
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 × )] × (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[]
Damage Barrier[]
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[]
Passive
Self
- 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[]
- 1 Requires talent.
- 2a Requires Aghanim's Scepter.
- 2b Requires Aghanim's Shard.
Creeps[]
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 (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 0.6/0.4/0.2/0, reducing the base magic resistance down to 15%/10%/5%/0%.
- Radius: 350
Base Magic Resistance Reduction: 40%/60%/80%/100%
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. - Radius: 350
Base Magic Resistance Reduction: 40%/60%/80%/100%
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 1 second.
Pure Damage[]
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[]
- Anti-Mage – Counterspell
- Arc Warden – Magnetic Field (Radiant)2b
- Arc Warden – Magnetic Field (Dire)2b
- Brewmaster – Drunken Brawler Earth Stance
- Centaur Courser – Cloak Aura
- Doom – Devour1
- Dragon Knight – Black Dragon Form2a
- 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[]
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.
- Black King Bar – Avatar
- Clockwerk – Power Cogs1
- Dawnbreaker – Starbreaker2b
- Earth – Debuff Immunity
- Elder Titan – Astral Spirit2b
- Grimstroke – Dark Portrait
- Huskar – Life Break
- Juggernaut – Blade Fury
- Legion Commander – Press the Attack1
- Lifestealer – Rage
- Lion – Mana Drain2b
- Omniknight – Repel
- Pangolier – Roll Up
- Pangolier – Rolling Thunder
- 1 Requires talent.
- 2a Requires Aghanim's Scepter.
- 2b Requires Aghanim's Shard.
Talents[]
Passive
Self
- 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 |
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
- 80% Magic Resistance for Chaotic Offering Golems:
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.
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 | 25 | 3600 | 144 |
Glimmer Cape | 25 | 2150 | 86 |
Mage Slayer | 20 | 2825 | 141.25 |
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[]
- 1 Requires talent.
- 2a Requires Aghanim's Scepter.
- 2b Requires Aghanim's Shard.
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.
- 2a Requires Aghanim's Scepter.
- 2b Requires Aghanim's Shard.
Illusions Negation[]
Innate
Self
- 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.
- A unit that has a +30% Magic resistance and another +40% Magic resistance means that it has a
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 = (Magic Damage Multiplieri )
- For base magic resistance,
Magic Damage MultiplierBase = [1 - Negation Multiplier × (0.25 + 0.001 × )]
- For base magic resistance,
- For other magic resistance sources,
Magic Damage Multiplieri = 1 - Magic Resistance
- For other magic resistance sources,
In full equation,
Total Magic Resistance = 1 - [1 - Negation Multiplier × (0.25 + 0.001 × )] × (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: 0.45, 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 will now be multiplied by 0.33. His current total magic resistance in this example is 1 - 0.33 = 67%.
- 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: -0.35, Decrepify: -0.6, 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 will now be multiplied by 1.62. Her current total magic resistance in this example is 1 - 1.62 = -62%.
- 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 = CurrentHP / 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
- EHPmagic
- = 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: -0.35, Decrepify: -0.6
- Final Magic Damage Multiplier
- = (1 - 0.278) * (1 - -0.35) * (1 - -0.6)
- = 1.55952
- EHPmagic
- = 1022 / 1.55952
- = 655
- Marci has 655 EHP against magical damage in this example.
Recent Changes[]
- ADDEDnew 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
- 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
- Fixed magic damage sources from attacks not being blocked by magic damage barrier type abilities (i.e. Barrier, Flame Guard etc.).
- Fixed Phantom Edge not stacking with other magic resistance sources.