Spell Damage

• Attack Damage
• Heroes' Main Attack Damage
• Spell Damage
• Damage Types

Spell damage ( <math>Sp</math> ) 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 3 damage types — magical, physical or pure damage.

Magic spell damage is influenced by magic resistance, physical spell damage is influenced by armor and pure damage is not affected by either. All three underlie damage manipulation.

Spell Damage Manipulation

Main Article: Damage manipulation

Stacking

All sources of spell damage manipulation stack additively within two categories, outgoing and incoming, which are then multiplied together. The two categories Outgoing Spell Damage Manipulation and Incoming Spell Damage Manipulation stack additively with Generic Incoming Damage Manipulation and Generic Outgoing Damage Manipulation respectively as spell damage manipulation is considered to be just a part of Damage manipulation. Since these are handled separately, the same category stack additively while different categories stack multiplicatively with each other.

For example, spell damage dealt by summons, unless otherwise stated, are not affected by the outgoing spell damage manipulation of the hero. However, summons can be affected by incoming spell damage manipulation since incoming spell damage manipulation affects the target of the damage instead of the caster.

Spell Damage Multiplier is defined as:

<math>

\text{Spell Damage Multiplier} = \big( 1 + \sum (\text{Outgoing Manip}) \big) \times \big( 1 + \sum (\text{Incoming Manip}) \big) </math>

Example 1: Outgoing Manipulation

Bloodseeker with a level 4 Bloodrage buff with Kaya and Sange. What is his current spell damage multiplier?

Spell damage amplification values:

• Level 4 Bloodrage: 0.3
• Kaya and Sange: 0.12

<math>

Sp_{Mu} = (1 + 0.3 + 0.12) \times (1 + 0) = 1.42 </math>

Bloodseeker's spell damage multiplier is 1.42 in this example.

Example 2: Incoming and Outgoing Manipulation

Bloodseeker from the previous example has Dagon 5 and is affected by Mage Slayer. How much actual spell damage Energy Burst will be dealt to Marci if she is also affected by Magic Weakness (before magic resistance reductions)?

• Dagon 5 spell damage: 800
• Incoming Spell Damage Manipulation: Magic Weakness: 2
• Outgoing Spell Damage Manipulation: Bloodrage: 0.3, Kaya and Sange: 0.12, Mage Slayer: -0.25

<math>\begin{align}

Sp_{Mu} &= \underbrace{ (1 + (0.3 + 0.12 - 0.25)) }_\text{Outgoing} \times \underbrace{ (1 + 2) }_\text{Incoming} \\ &= \underbrace{ (1.17) }_\text{Outgoing} \times \underbrace{ (3) }_\text{Incoming} \\ &= 3.51 \end{align} </math>

<math>

\text{Total Spell Damage} = 800 * 3.51 = 2808 </math>

Marci affected by Magic Weakness will take 2808 spell damage (before magic resistance) from Bloodseeker in this example.

Example 3: Generic Damage Manipulation

Bloodseeker from the previous example instead chooses to cast his Dagon 5 on a Spectre with level 4 Dispersion. Assuming all other modifiers are the same, how much spell damage will be dealt to Spectre (before magic resistance).

Dispersion is generic damage manipulation, meaning it affects all damage dealt to [[spectre|]]. Despite this, it stacks additively with other incoming spell damage manipulation like Magic Weakness when calculating spell damage.

• Dagon 5 spell damage: 800
• Incoming Spell Damage Manipulation: Magic Weakness: 2
• Incoming Generic Damage Manipulation: Dispersion: -0.2
• Outgoing Spell Damage Manipulation: Bloodrage: 0.3, Kaya and Sange: 0.12, Mage Slayer: -0.25

<math>\begin{align}

Sp_{Mu} &= \underbrace{ (1 + (0.3 + 0.12 - 0.25)) }_\text{Outgoing} \times \underbrace{ (1 + 2 - 0.2) }_\text{Incoming} \\ &= \underbrace{ (1.17) }_\text{Outgoing} \times \underbrace{ (2.8) }_\text{Incoming} \\ &= 3.276 \end{align} </math>

<math>

\text{Total Spell Damage} = 800 * 3.276 = 2620.8 </math>

Spectre affected by will take 2620.8 spell damage (before magic resistance) from Bloodseeker in this example.

Outgoing Spell Damage Manipulation

A unit that has outgoing spell damage manipulation deals more or less spell damage with any spell damage they apply to any unit. Multiple sources of outgoing spell damage manipulation stack additively.

Outgoing Spell Damage Amplification Sources

• Alchemist – Aghanim's Scepter Synth
• Bloodseeker – Bloodrage
• Oracle – False Promise^2a
• Io – Overcharge
• Lina – Flame Cloak
• Morphling – Morph^2a
• Muerta – Pierce the Veil^2b
• Rubick – Arcane Supremacy
• Rubick – Spell Steal¹

Outgoing Spell Damage Reduction Sources

• Anti-Mage – Counterspell^2b
• Bloodthorn – Mage Slayer
• Mage Slayer – Mage Slayer

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Talents

Spell Damage Amplification

Ability
Passive

Affects
Self

There is no description for this ability.

Spell Damage Amp: Varies

NOTES

 

6162, 6015, 5948, 5996, 522, 5949, 511, 5989, 444, 6326, 7401, 6055, 456, 743, 6236, 6327

special_bonus_spell_amplify_3/4/5/6/7/8/9/10/11/12/14/15/16/18/19/20/25

• Increases the hero's outgoing spell damage amplification.

• The following values exist:
  • 3%/4%/5%/6%/7%/8%/9%/10%/11%/12%/14%/15%/16%/18%/19%/20%/25%

The following heroes have a talent that grants them outgoing spell damage amplification.

Bonus	Level 10		Level 15		Level 20		Level 25
	Left	Right	Left	Right	Left	Right	Left	Right
Spell Amplification	+8%

Item Sources

Many items grant their owners a spell damage amplification bonus by giving them a direct bonus. The effects are limited to the item's owner, which must have the item equipped.

Spell Damage Amplification Items

Item	Value	Item Cost	Cost/Value Point
Fairy's Trinket	5%	N/A	N/A
Kaya	10%	2100	210
Kaya and Sange	12%	4200	350
Meteor Hammer	10%	2850	285
Timeless Relic	15%	N/A	N/A
Yasha and Kaya	12%	4200	350
Values do not include portions from actives or auras.

For Kaya-based items: Multiple sources of spell damage amplification do not stack.

Incoming Spell Damage Amplification

A unit that has incoming spell damage amplification debuff on them takes more spell damage, and multiple sources of incoming spell damage amplification stack additively. Incoming spell damage amplification affects every source of spell damage, except for damage flagged as HP Removal.

Abilities

Incoming Spell Damage Amplification Sources

• Ancient Black Drake – Magic Amplification Aura
• Beastmaster – Wild Axes
• Courier – Passive Bonus
• Grimstroke – Soulbind¹
• Hoodwink – Hunter's Boomerang
• Nyx Assassin – Vendetta^2b
• Undying – Flesh Golem
• Veil of Discord – Magic Weakness

¹ Requires talent.

^2a Requires Aghanim's Scepter.

^2b Requires Aghanim's Shard.

Exceptions

Main Article: Abilities with the No-Spell-Amplification flag

There are certain cases of abilities that ignore both types of spell damage amplification, and those abilities usually cannot spell lifesteal. In general, abilities with health manipulation mechanics (Instant Kill, HP Removal, Delayed Damage etc.) are not affect by both types of spell damage amplifications.

However, the following abilities are affected by Hunter's Boomerang's incoming spell damage amplification:

Abilities Not Affected by Outgoing Spell Damage Amplifications

• Battle Fury – Cleave
• Blade Mail – Damage Return
• Chipped Vest – Passive
• Kunkka – Tidebringer
• Luna – Moon Glaives
• Magnus – Empower
• Nyx Assassin – Spiked Carapace
• Silencer – Glaives of Wisdom¹
• Storm Spirit – Overload²
• Sven – Great Cleave
• Templar Assassin – Psi Blades
• Tiny – Tree Grab
• Tiny – Tree Throw
• Witch Doctor – Death Ward³

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

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

³ The damage of the bouncing attacks count as spell damage, but are unaffected by outgoing spell damage amplification.

Version History

Version

Description

7.30e
(2021-10-28)

• Magic Weakness no longer amplifies spell damage that is not affected by outgoing spell damage amplification. [?]

7.06c
(2017-05-29)

• Damage return from Blade Mail is no longer increased by outgoing spell amplification.

7.00
(2016-12-12)

• Moon Glaives no longer gets boosted by outgoing spell amplification.
• Cleave no longer gets boosted by outgoing spell amplification.
• Spell lifesteal does not trigger heal for things that don't receive spell amplification ( Moon Glaives, Cleave).

Patch History

Patch

Description

08 Aug 2019

• Alt now show their modified/increased spell ampification values at tooltips.