Magic Resistance

Magic resistance is an attribute of heroes, extremely similar to armor. Instead of reducing physical damage, it reduces magical damage. All heroes, except Meepo, possess 25% magic resistance from their armor type. This percentage is completely independent of their amount of armor. Certain Hero summons, such as Enigma's Eidolons, also possess intrinsic magic resistance.

Magical Damage
Magical damage is a special damage type caused mostly by abilities. Unlike physical damage, it isn't reduced by armor. However, it is reduced by magic resistance, and will not affect targets that are magic immune or buildings that are fortified. Ethereal units will also take 40% amplified magical damage.

Mixed damage is similar to magical damage. It is reduced by magic resistance and armor, but ignores magic immunity. Mixed damage does not affect ethereal units.

Damage Reduction
All Heroes have a natural 25% magic resistance, except for Meepo and his clones, who have 35%. This means that, by default, for most heroes, all magical damage is reduced by 25%, or only 75% of the ability's damage. Any additional effects, such as the bonus given by Hood of Defiance, will reduce the remaining damage by their resistance.


 * Actual damage = magical damage × (1 + magic amplification) × (1 − natural resistance) × (1 − magic resistance of item) × (1 − magic resistance of first ability) × (1 − magic resistance of second ability)

In the formula above, natural resistance is 0.25 for all heroes except 0.35 for Meepo.

Magic resistance items do not stack. Only the most powerful magic resistance effect in a Hero's inventory will provide a bonus. Stacking magic resistance of different types (natural, from item, from ability) occurs multiplicatively. For example, an Anti-Mage with Spell Shield, and Hood of Defiance will have 73.75% magic resistance (in other words will only receive 26.25% of any magical damage).

Sources of Magic Resistance

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Magic Amplification
Magical damage can also be amplified, it also stacks multiplicatively. For example, if a target is both Ethereal and under the effect of a Veil of Discord, the total amplification will be 75% (1.4*1.25).

Sources of Magic Amplification

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