Damage is any means by which unit's current health can be reduced. The 3 main damage classifications are Physical and Pure.

Damage Sources

Damage can come from attacks, abilities and items. Attack damage is the damage dealt per attack, and is displayed on the sword icon in the HUD. Generally, damage sources are split into two big categories — Attack Damage and Spell Damage.

Attack damage ( ${\displaystyle A}$ ) is the amount of damage a unit is shown to deal with a regular attack. A unit's total attack damage is the sum of its main attack damage (white) and bonus attack damage (green). Most attack damage are physical damage, however, there are some exceptions to this.

Spell damage ( ${\displaystyle Sp}$ ) is usually damage dealt in a separate instance from attack damage, with some exceptions. This includes all abilities (including item abilities and attack modifiers) which deal the 2 damage types — physical or pure damage.

Damage Classification

All forms of damage in Dota 2 are classified by damage types. There are 3 primary damage types: Physical, and Pure.

Physical Damage is reduced by Armor or Damage Block, while Pure Damage is not generally reduced by anything (except for damage reduction, e.g. Enrage and Defense Matrix, which affects all damage types).

All 3 damage types have some interaction with other damage-related game mechanics as noted in the table below. Some damage sources may also have the HP Removal flag, causing the damage to ignore some mechanics which would manipulate it otherwise.

Mechanic	Damage Type Interaction
	Physical Attacks	Physical Abilities	Pure Attacks	Pure Abilities
Armor	Reduced	Reduced	-	-	-	-
Damage Block	Reduced	Normal1	-	-	-	-
Ethereal			Amplified	Amplified	-	-
Evasion	May Miss	-	May Miss	-	May Miss	-
Invulnerability	No effect on all damage types.
Damage Manipulation2	Amplifies, Reduces and Negates all damage types.
Damage Negation2

¹ Except Moon Glaives, although considered as spell damage, its damage is blocked.

{{Footnote|2|These categories only count ability effects which directly manipulate damage, reducing (e.g. Bristleback), amplifying (e.g. Bloodrage) or completely negating them (e.g. Refraction).

Debuff Immunity

Debuff immunity is a modifier which stops most effects of debuffs' effects on a unit without dispelling the debuffs and without preventing debuffs from being placed on the unit. It also grants immunity against pure and reflected damage, as well as protecting against mana loss.

Debuff immunity inherently grants the unit nothing, with the amount depending on the source ability. On top of this, it also grants 100% resistance against pure damage and reflected damage, meaning they deal 0 damage. Note that a 0 damage instance is still registered and still may proc on-damage effect, unless it is flagged as HP Removal.

Physical damage does not interact with debuff immunity at all, regardless of whether the ability pierces debuff immunity or not.

Physical

Most attack damage from all units (including buildings) and certain abilities deal physical damage, unless stated otherwise. The total physical damage dealt to a unit is affected by armor (percentage reductions) and damage block (flat reductions). Units under ethereal are not affected by physical damage.

Some abilities (e.g. Guardian Angel and Cold Embrace) provides physical damage immunity, although they can still be targeted by attacks and abilities.

Physical damage from abilities (and theoretically items) is usually unaffected by defense class. Unless it directly manipulates the attack damage (i.e. attack damage increasing abilities or Exorcism). Physical damage (except for Moon Glaives) from these attack damage increasing abilities are affected by armor, but are not affected by evasion and damage block.

The following abilities deal physical damage (summoning abilities and attack damage buffs are not listed):

¹ Damage is directly added to the total attack damage.

² Damage from these abilities is affected by defense class as well.

³ Full damage dealt is physical

⁴ Damage dealt is blocked by damage block.

Pure

Pure Damage is a damage type that is not reduced by Armor. It is also not amplified, 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.

For example, Laser deals pure damage, but cannot be cast on units with spell immunity.

¹ Mist Coil deals pure damage to the caster, but physical damage to the target.

² Requires a talent.

³ Requires Aghanim's Scepter.

⁴ Requires Aghanim's Shard.

Flags

Several abilities have certain flags that cause them to behave differently in certain situations, all abilities can be flagged, regardless of damage types. Examples of flags include the HP Removal, the No-reflection, the No-Spell-Lifesteal and the No-Spell-Amplification flag.

HP Removal

Abilities with the HP Removal flag ignore and do not trigger any on-damage effects, making them unable to interrupt Blink Dagger or cancel consumables (e.g. Clarity). Their damage also cannot be amplified or negated by most forms of generic damage manipulation and damage negation. In some cases, their damage ignores invulnerability as well. Damage ignored this way is still registered as such and may be counted for statistic purposes.

¹ Maximum health as cost per second is considered HP Removal to the caster.

² This ability delays damage. The delayed damage is Pure and has the HP Removal flag.

Setting Health

Besides healing and damaging, a unit's health may also be directly altered by setting it to certain values. Health altered this way is neither registered as a heal, nor as damage, and therefore is ignored by anything that reacts to healing and damage. It can also never be lethal, and can never set the health beyond the unit's max health. When casting the following abilities with lesser health than the health cost, the caster's goes down to 1_HP.

HP Removal is not the same as Setting Health. HP Removal is still damage, but flagged to bypasses several but not all on-damage effects, and can still be lethal.

On-Damage Effects

Besides all sources of damage manipulation and spell lifesteal, the following abilities do not react on damage which has the HP Removal flag:

No-reflection

On-damage events of certain abilities do not to interact with the damage of abilities which have the no-reflection flag. This is to prevent infinite damage loops in case of 2 opposing heroes with Blade Mails.

¹ Triggers on damage effects of all abilities, except from the following list.

² Does not trigger on damage effects.

³ Flagged as HP Removal.

The following abilities do not react to abilities with the No-reflection flag:

No-Spell-Lifesteal

Abilities with the no-spell-lifesteal flag cannot spell lifesteal, even though their damage is categorised as spell damage.

¹ The damage of the bouncing attacks is unable to spell lifesteal. The -based damage is able to spell lifesteal, including that of the bounces.

² The damage of the bouncing attacks is unable to spell lifesteal. However, Overload's area damage is able to spell lifesteal, including that of the bounces.

³ The damage of the bouncing attacks count as spell damage, but is unable to spell lifesteal.

No-Spell-Amplification

Abilities with the no-spell-amplification flag ignore all sources of spell damage amplification (except for Hunter's Boomerang), even though their damage is categorised as spell damage.

¹ The damage of the bouncing attacks is unaffected by spell damage amplification. The -based damage is fully affected, including that of the bounces.

² The damage of the bouncing attacks is unaffected by spell damage amplification. However, Overload's area damage is fully affected, including that of the bounces.

³ The damage of the bouncing attacks counts as spell damage, but is unaffected by spell damage amplification.

No-multiplier

The no-multiplier flag causes generic damage manipulation to not interact with the flagged damage.

¹ Maximum health as cost per second has the no-multiplier flag.

² This ability delays damage. The delayed damage has the no-multiplier flag.

³ Current health as cost per second has the no-multiplier flag.

Instant Kill

This mechanic kill units without the actual use of damage. Similar to HP Removal, the instant kill effect ignores almost all damage manipulations and can only be prevented by a few abilities.

The most prominent example that uses this mechanic is expiring summoned units and illusions, which are killed once their set duration ends. Summons and illusions that get replaced on cast are killed this way as well. Min health via damage manipulation does not prevent instant kill.

Abilities that prevent or bypass instant killing usually have special interactions hard-coded into the abilities.

Illusions

These abilities instantly destroy illusions when used on them, unless the illusions are strong illusions.

¹ Instantly kills the target upon landing if it is not a hero or a clone.

² Requires a talent.

³ Requires Aghanim's Scepter.

⁴ Requires Aghanim's Shard.

⁵ Kills illusions on the first tick, not upon cast.

Creeps

¹ Instantly kills the oldest captured unit if the max amount of units gets exceeded.

² Requires a talent.

³ Requires Aghanim's Scepter.

⁴ Requires Aghanim's Shard.

⁵ Instantly kills the target if their current health is below the threshold.

⁶ Instantly kills the target upon landing if it is not a hero or a clone.

Forced Kill

The following abilities use the instant kill mechanic to forcefully remove or kill its unit(s) from the game when certain conditions are met.

Damage Manipulation

Damage manipulation is a mechanic that alters damage values, either increasing or reducing it.

Trivia

The following damage types were removed in version 6.82.

Composite

Composite damage (also known as mixed damage) was a damage type that was reduced by both armor. It pierced spell immunity and did not affect ethereal units. This damage type was used by Acid Spray, Wild Axes, Diabolic Edict, Summon Spirit Bear's backlash damage, Land Mines and Suicide Squad, Attack!.

All of them were changed to physical damage, except for the backlash damage from the Spirit Bear, which was changed to pure damage.

Universal

Universal damage was a damage type that pierced spell immunity and was affected by something else. This damage type was previously used by Pulverize, Doom, Echo Slam's initial damage, Midnight Pulse, Laguna Blade, March of the Machines and Flaming Fists.

Doom, Midnight Pulse, Flaming Fists and Laguna Blade were changed to deal pure damage, allowing them to still pierce spell immunity, while Pulverize, Echo Slam's initial damage and March of the Machines were changed to deal physical damage, and thus no longer pierce spell immunity.

v • d • e Mechanics Main Heroes Unit Type (Heroes / Clones / Illusions) Complexity Attributes Table Buyback Level Roles Gold Experience Animations Stats Armor Attributes ( Strength / Agility / Intelligence / Charisma) Health & Mana (HP Regen & MP Regen) Movement Speed / Slow Resistance Status Resistance Turn Rate Misc Creep Controling Death / Denying Vision Unit Size (Collision Size / Bound Radius / Selection Box / Model Size) Gib Type / Shades Adjectives Buildings Towers / Barracks / Ancient / Fountain Effigy Neutral Buildings (Outposts / Watchers / Twin Gates / Lotus Pools) Abilities Type Active / Passive / Autocast Aura Accuracy / Evasion Channeling Damage Barrier Damage Block Damage Manipulation Damage Over Time Talents Teleport Targeting Area No Target Point Unit Vector Combinations Casting Cast Range / Motion Buffer Cast Animation (Cast Point + Backswing) Cooldown Reduction (Flat / Current Flat / Percentage) Reset Charge-based Runes Bounty Rune Water Rune Wisdom Rune Power Runes ( Amplify Damage Rune / Arcane Rune / Haste Rune / Illusion Rune / Invisibility Rune / Regeneration Rune / Shield Rune) Misc Random Distribution Transformation Attack Damage Attack Damage Instant Attack Heroes Attack Classes Attack Range (Acquisition Range) Attack Speed (BAT / Interval) Damage Types (Physical / Pure / Instant Kill) Flags (HP Removal / No-reflection / No-Spell-Lifesteal / No-Spell-Amplification) Projectile Speed Spell Damage (Outgoing / Incoming) Modifiers Bash Cleave / Splash Corruption Critical Strike Lifesteal / Spell Lifesteal Mana Break On-hit Effects Misc Damage Instance Animation / Orb Walking Status Effects Disables Cyclone Disabling Orders Forced Movement (Knockback) / Upward Movement Fear (Hypnosis) Hide Hex Root Leash Stun Sleep Taunt Movement Move Speed Slow Flying Movement Phased / Tree Walk / Unobstructed Movement Other Attack Immune / Non-targetable Attack Speed Slow Debuff Immunity Spell Immunity Invulnerability Invisibility Blind Break Disarm Ethereal Silence Mute Trap Dispels Basic Strong Death Items Mechanics Courier Sharing / Selling Disassemble Recipes Neutral Item Drop