Magic resistance

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Counterspell icon.png
▶️ Thy magic harms me not.
Anti-Mage

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

Each point of strength increases a hero's magic resistance by 0.08.

Base magic resistance[edit]

Base magic resistance is a value that never changes throughout a game. It consists of one fixed value set for each unit individually. The base magic resistance of a unit can be a negative number.

Heroes[edit]

Heroes Magic resistance
Abaddon, Alchemist, Ancient Apparition, Anti-Mage, Arc Warden, Axe, Bane, Batrider, Beastmaster, Bloodseeker, Bounty Hunter, Brewmaster, Bristleback, Broodmother, Centaur Warrunner, Chaos Knight, Chen, Clinkz, Clockwerk, Crystal Maiden, Dark Seer, Dark Willow, Dazzle, Death Prophet, Disruptor, Doom, Dragon Knight, Drow Ranger, Earth Spirit, Earthshaker, Elder Titan, Ember Spirit, Enchantress, Enigma, Faceless Void, Grimstroke, Gyrocopter, Huskar, Invoker, Io, Jakiro, Juggernaut, Keeper of the Light, Kunkka, Legion Commander, Leshrac, Lich, Lifestealer, Lina, Lion, Lone Druid, Luna, Lycan, Magnus, Mars, Medusa, Meepo, Mirana, Monkey King, Morphling, Naga Siren, Nature's Prophet, Necrophos, Night Stalker, Nyx Assassin, Ogre Magi, Omniknight, Oracle, Outworld Devourer, Pangolier, Phantom Assassin, Phantom Lancer, Phoenix, Puck, Pudge, Pugna, Queen of Pain, Razor, Riki, Rubick, Sand King, Shadow Demon, Shadow Fiend, Shadow Shaman, Silencer, Skywrath Mage, Slardar, Slark, Sniper, Spectre, Spirit Breaker, Storm Spirit, Sven, Techies, Templar Assassin, Terrorblade, Tidehunter, Timbersaw, Tinker, Tiny, Treant Protector, Troll Warlord, Tusk, Underlord, Undying, Ursa, Vengeful Spirit, Venomancer, Viper, Visage, Warlock, Weaver, Windranger, Winter Wyvern, Witch Doctor, Wraith King, Zeus 0.25

Creeps[edit]

Units Magic resistance
Alpha Wolf, Ancient Black Drake, Ancient Prowler Acolyte, Ancient Prowler Shaman, Centaur Conqueror, Centaur Courser, Dark Troll Summoner, Fell 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, Ogre Bruiser, Ogre Frostmage, Ranged Creep, Satyr Banisher, Satyr Mindstealer, Satyr Tormenter, Super Melee Creep, Super Ranged Creep, Vhoul Assassin, Wildwing, Wildwing Ripper 0%
Mud Golem, Shard Golem 50%
Roshan 55%
Ancient Black Dragon, Ancient Granite Golem, Ancient Rock Golem, Ancient Rumblehide, Ancient Thunderhide 70%
Siege Creep, Super Siege Creep 80%

Summons[edit]

Summons Magic resistance
Astral Spirit, Boar, Earth, Fire, Forged Spirit, Greater Treant, Hawk, Skeleton Warrior, Spirit Bear, Storm, Treant 0%
Undying Zombie, Warlock's Golem 33%
Familiar 35%
Necronomicon Archer, Necronomicon Warrior, Spiderite, Spiderling 40%
Eidolon, Wraith King Skeleton 50%
Lycan Wolf, Lycan Wolf (Aghanim's Scepter) 70%

Stacking[edit]

All sources of magic resistance stack multiplicatively. This means a unit's magic resistance value changes less the higher its magic resistance is, and more the lower it is. This prevents a unit from reaching 100% magic resistance by stacking different sources up.

There are several abilities that set a unit's magic resistance to 100%. Besides them, the magic resistance granted by strength can theoretically reach 100% as well, since the bonus from strength gets summed up into, and treated as one instance. This means that heroes can theoretically reach 100% magic resistance with 1250 strength.

Formula

For total magic resistance of a unit (multiply the result by 100 to get the percentage value):

Total magic resistance = 1 − ((1 − natural resistance) × (1 - strength × 0.08%) × (1 − first resistance bonus) × (1 − second resistance bonus) × (1 + first resistance reduction) × (1 + second resistance reduction))

For magical damage after magic resistance:

Actual damage = magical damage × (1 − natural resistance) × (1 - strength × 0.08%) × (1 − first resistance bonus) × (1 − second resistance bonus) × (1 + first resistance reduction) × (1 + second resistance reduction)

Example:

Anti-Mage minimap icon.png Anti-Mage with level 4 Counterspell and a Cloak icon.png Cloak has a magic resistance of:
1 - (1 - 0.25) × (1 - 0.45) × (1 - 0.15) = 64.9375%
Visage minimap icon.png Visage on level 25 under the effect of Veil of Discord icon.png Veil of Discord and a level 4 Decrepify cast by an enemy has a magic resistance of:
1 - (1 - 0.25) × (1 - (89.2 × 0.08)) × (1 + 0.25) × (1 + 0.6) = -39.296%

Effective HP[edit]

The extra damage a unit can take due to magic resistance is known as its extra effective HP (or EHP) for magical damage. Despite each source of magic resistance increasing the magic resistance value less the higher it is and making them seem less effective, each sources increases the unit's effective HP against magical damage by their base value. A unit with 0% magic resistance has 100% effective HP against magical damage, means magical damage equaling 100% of its health is required to kill it. Most heroes have 0.25 magic resistance by default, making their effective HP against magical damage 133.33%.

Magic resistance -100% -75% -50% -25% -10% 0% 10% 25% 50% 75% 100%
Effective HP 500 571 667 800 909 1000 1111 1333 2000 4000
Calculating effective HP
Effective HP = Total HP / (1 - magic resistance)

Instead of diminishing in effectiveness, multiple sources of resistance are actually more effective stacked than they are individually. Two sources of 25% resistance stacked provides 78% extra effective HP whereas one source provides 33%.

Example
Anti-Mage minimap icon.png Anti-Mage has 1280 health at max level. With his basic magic resistance, max level Counterspell and a Cloak icon.png Cloak, he has an effective HP of:
1280 / (1 - 64.9375 × 0.01) = 3650.62 effective HP
Visage minimap icon.png Visage has 1980 health at max level. With his basic magic resistance, while under the effect of Veil of Discord and an enemy level 4 Decrepify, he has an effective HP of:
1980 / (1 - -50 × 0.01) = 1320 effective HP

Modifying magic resistance[edit]

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

Magic resistance increasing abilities[edit]

Besides spell immunity, which always grants 100% magic resistance, the following abilities increase magic resistance:

Magic resistance increasing abilities
  • Counterspell icon.png
    Magic resistance bonus: 15%/25%/35%/45% (Talent 40%/50%/60%/70%)
    Passive.
  • Cloak Aura (Centaur Courser) icon.png
    Hero magic resistance bonus: 10%
    Non-hero magic resistance bonus: 20%
    Aura, affects nearby allies. Multiple instances fully stack. The buff lingers for 0.5 seconds.
  • Glimmer Cape icon.png
    Magic resistance bonus: 45%
    Duration: 5
    Affects the target ally. The magic resistance is only applied when fully invisible. It is not applied during the fade time.
  • Cloak Aura (Hellbear) icon.png
    Hero magic resistance bonus: 10%
    Non-hero magic resistance bonus: 20%
    Aura, affects nearby allies. Multiple instances fully stack. The buff lingers for 0.5 seconds.
  • Fate's Edict icon.png
    Magic resistance: 100%
    Duration: 3/3.5/4/4.5
    Affects the target unit.
  • Pipe of Insight icon.png
    Magic resistance bonus: 10%
    Aura, affects nearby allies. The buff lingers for 0.5 seconds.
  • Demolish (Spirit Bear) icon.png
    Magic resistance bonus: 33%
    Passive.
  • Corrosive Skin icon.png
    Magic resistance bonus: 10%/15%/20%/25% (Talent 16%/21%/26%/31%)
    Passive.

Magic resistance reducing abilities[edit]

The following abilities reduce magic resistance:

Magic resistance reducing abilities
  • Ice Vortex icon.png
    Magic resistance reduction: 15%/20%/25%/30% (Talent 23%/28%/33%/38%)
    Duration: 16
    Aura, affects enemies within the target area. The debuff lingers for 0.5 seconds.
  • Natural Order icon.png
    Base magic resistance negation: 40%/60%/80%/100%
    Aura, affects enemies within range of the Unknown Unit icon.png Astral Spirit. The reduction is based on the enemies' base magic resistance. The debuff lingers for 1 seconds.
  • Ethereal Blade icon.png
    Magic resistance reduction: 40%
    Ally duration: 4
    Enemy duration:
    Affects the target unit. The magic resistance reduction of multiple ethereal effects does not stack, the one with higher value takes priority.
  • Ghost Scepter icon.png
    Magic resistance reduction: 40%
    Duration: 4
    Affects the caster. The magic resistance reduction of multiple ethereal effects does not stack, the one with higher value takes priority.
  • Ghost Shroud icon.png
    Magic resistance reduction: 40%
    Duration: 3/3.5/4/4.5
    Affects the caster. The magic resistance reduction of multiple ethereal effects does not stack, the one with higher value takes priority.
  • Decrepify icon.png
    Ally magic resistance reduction: 25%
    Enemy magic resistance reduction: 30%/40%/50%/60%
    Duration: 3.5 (Talent 5.5)
    Affects the target unit. The magic resistance reduction of multiple ethereal effects does not stack, the one with higher value takes priority.
  • Ancient Seal icon.png
    Magic resistance reduction: 30%/35%/40%/45% (Talent 45%/50%/55%/60%)
    Duration: 3/4/5/6
    Affects the target enemy.
  • Veil of Discord icon.png
    Magic resistance reduction: 25%
    Duration: 16
    Affects all enemies within the target area.
  • Nethertoxin icon.png
    Magic resistance reduction: 10%/15%/20%/25%
    Duration: 8
    Aura, affects enemies within the target area. The debuff lingers for 0.5 seconds.

Magic resistance granting talents[edit]

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
  • Death Prophet minimap icon.png +15%
  • Enigma minimap icon.png +15%
  • Enchantress minimap icon.png +15%
  • Vengeful Spirit minimap icon.png +15%
  • Brewmaster minimap icon.png +20%
  • Elder Titan minimap icon.png +15%
  • Necrophos minimap icon.png +20%
  • Keeper of the Light minimap icon.png +40%
  • Clockwerk minimap icon.png +50%
  • Earthshaker minimap icon.png +50%

Magic resistance granting items[edit]

These items grant bonus magic resistance to the hero who has them equipped.

Magic resistance granting items
Item Value Item cost Cost per value point
Bracer icon.png Bracer 6 515 85.83
Cloak icon.png Cloak 15 550 36.67
Glimmer Cape icon.png Glimmer Cape 15 1950 130
Holy Locket icon.png Holy Locket 15 2700 180
Hood of Defiance icon.png Hood of Defiance 25 1700 68
Pipe of Insight icon.png Pipe of Insight 30 3025 100.83

Magical damage barrier[edit]

Magical damage barriers absorb a set amount of magical damage, no matter whether it comes from spells (magical spell damage) or attacks (magical attack damage). They absorb the damage before it is reduced by magic resistance, unless the resistance is provided by spell immunity. This means when a hero with for example 25% magic resistance and a 300 health damage barrier gets hit by 400 magical damage, the shield will absorb 300 of that. The exceeding 100 are not absorbed and are now reduced by the 25% magic resistance down to 75. So in this scenario, the hero takes 75 damage. This means a barrier is more effective the lower a unit's magic resistance is, similar to how damage block is more effective, the lower the armor is.

Multiple sources of magical damage barriers do not stack. When affected by multiple, all of them deplete at the same time. For example, if a unit is affected by a level 4 Flame Guard (500 barrier health) and by Pipe of Insight (400 barrier health), and then takes 300 magical damage, both shields lose 300 capacity, leaving Flame Guard with 200 and Pipe of Insight 100 absorb capacity.

Sources of magic damage barriers