There are several ways to affect the final value of a damage instance. Damage can be manipulated on both ends, from the dealing unit (outgoing damage) and the receiving unit (incoming damage). Armor and magic resistance are the most common damage manipulators, affecting incoming physical and magical damage respectively (no similar trait exists for pure damage). They usually reduce damage, but can also amplify it if their values are negative. Spell damage amplification is the main trait for amplifying (but not for reducing) outgoing spell damage (no similar trait exists for attack damage). Besides these, there are some other ways to manipulate damage, ranging from amplifying damage, reducing damage and even negating damage completely.
Sources of damage manipulation
Amplifying incoming damage
Damage amplification causes afflicted units to take additional damage.
Amplifying outgoing damage
Besides spell damage amplification, these abilities amplify outgoing damage.
Reducing incoming damage
Just like how damage can be amplified, it can also be reduced.
- Damage Reduction: 100%
- Rear Damage Reduction: 16%/24%/32%/40%
Side Damage Reduction: 8%/12%/16%/20%
Reduces damage for Bristleback when taking damage from his rear or sides.
- Damage Reduction: 40%
Illusion Damage Reduction: 75%
Reduces damage from all sources (more from illusions) while under Backdoor Protection. Also reduces damage from illusions by 50% while not protected.
- Based on the ability the illusion is created by, it may take less damage than the hero it is based on.
- Damage Reduction: 40%
Reduces damage for all buffed allies, making them take that portion of damage later.
- Damage Reduction: 70%
Damage Absorbed per Mana: 1.6/1.9/2.2/2.5
- Damage Reduction: 40%
- Damage Reduction per hero: 12%/14%/16%/18%
Reducing outgoing damage
These abilities are able to reduce outgoing damage.
Stacking damage reduction & amplification
Armor and magic resistance work separately from other damage manipulators. This means they always stack multiplicatively with any other listed ability.
Besides damage reducing and damage amplifying effects stack additively with each other. Borrowed Time, Ghostship and Mana Shield stack multiplicatively with them. Mana Shield also stacks multiplicatively with Borrowed Time and Ghostship. However, the damage reductions of Borrowed Time and Ghostship do not stack with each other, although both still react on the damage (Borrowed Time still heals Abaddon, and Ghostship's rum wear-off still counts the damage). The damage amplification which illusions usually have stacks multiplicatively with all other damage amplifying and reducing effects (considering they are able to affect illusions).'s aura, 's rum and , all
Examples of additive stacking (all values consider highest possible value, examples ignore armor and magic resistance, 100% is the base value):
- Ursa affected by
100 - 80 + 35 = 55% damage
100 - 22 - 40 = 38% damage
- A hero affected by
100 - 100 + 35 = 35% damage
Examples of multiplicative stacking:
- Medusa affected by
(100 + 35) * 30% = 40.5% damage
- Medusa affected by the same as above, but also additionally by
(100 + 35) * 30% * 60% = 24.3% damage
(100 + 35 - 40) * 320% = 304% damage
Stacking outgoing damage manipulation stacks in the same way as incoming damage manipulation, i.e. additively. However, since incoming and outgoing manipulations happen at different times (outgoing happens first), they stack multiplicatively with each other.
Damage negation causes entire instances of damage to deal no damage to its target, however, the instance is still registered. This means, if something reacts on damage without having a minimum damage threshold, it still reacts on the negated damage.
- Chance: 20%
- Negated Damage: 120
Can only negate magical damage. Can only negate a certain amount of damage per charge. Goes on cooldown upon negating an instance. Ignores damage lower than 50.
- Duration: 0.2
- Duration: 2.25
Can only negate 1 instance of damage from each player.
- Duration: 4
Can only negate physical damage.
Preventing on-damage effects
Many abilities react on damage a unit receives. In some cases, fully negating the damage causes them to not proc. However, some on-damage effects also react on 0 damage so they still may proc even when the proccing damage got negated.
The following abilities and effects do not react on damage when it gets fully negated (reduced to 0):
- Aegis of the Immortal – Expire Restore
- Ancient Black Dragon – Splash Attack1
- Blink Dagger – Blink
- Bloodthorn – Soul Rend
- Bottle – Regenerate
- Bristleback – Bristleback2
- Clarity – Replenish
- Healing Salve – Salve
- Heart of Tarrasque – Regeneration Amplification
- Lifesteal – All sources1 3
- Lifestealer – Open Wounds
- Mjollnir – Static Charge
- Monkey King – Tree Dance
- Octarine Core – Spell Lifesteal
- Orchid Malevolence – Soul Burn
- Pugna – Life Drain
- Regeneration Rune – Regeneration
- Spirit Vessel – Soul Release
- Templar Assassin – Psi Blades1
- Tidehunter – Kraken Shell2
- Urn of Shadows – Soul Release
- Visage – Soul Assumption2
1 These work when the damage gets negated by.
2 These abilities have damage counters, which do not work when the damage gets negated.
3 Includes all sources of lifesteal and spell lifesteal, except, and 's Spell Lifesteal, which are listed separately.
The following abilities still do react on fully negated damage:
- Bane – Nightmare
- Batrider – Sticky Napalm
- Battle Fury – Cleave
- Blade Mail – Damage Return
- Chen – Divine Favor
- Death Prophet – Exorcism
- Dragon Knight – Elder Dragon Form (splash damage)
- Elder Titan – Echo Stomp
- Kunkka – Tidebringer
- Lifestealer – Feast
- Lone Druid – Summon Spirit Bear
- Magnus – Empower
- Spectre – Dispersion1
- Spirit Bear – Return
- Sven – Great Cleave
- Tiny – Tree Grab
- Tiny – Tree Throw
- Viper – Corrosive Skin
- Warlock – Fatal Bonds1
1 The damage ofand the damage spread of are fully unaffected by any form of reduction, except for magic resistance and armor.
Min Health, just like regular damage negation, prevents a unit from dying. However, the way in which that is achieved is completely different. Instead of directly reducing or negating damage, this mechanic rather manipulates the health of the unit. This property (MODIFIER_PROPERTY_MIN_HEALTH) prevents a unit's health from dropping below the value it is set to. It does not affect the damage itself, meaning on-damage effects react on the full damage, and not how much damage was dealt effectively, so they can be triggered normally.
The following abilities use the Min Health mechanic:
- Min health: 1
- Max health as min health: 20%
When off cooldown, once the minimum health is reached, the owner gets strong dispelled and healed by 400 health.