Spell Damage

Spell damage ( $$Sp$$ ) 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 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.

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:



Example 1: Outgoing Manipulation

 * with a level 4 buff with . What is his current spell damage multiplier?
 * Spell damage amplification values:
 * Level 4 :




 * 's spell damage multiplier is in this example.

Example 2: Incoming and Outgoing Manipulation

 * from the previous example has and is affected by . How much actual spell damage  will be dealt to  if she is also affected by  (before magic resistance reductions)?
 * spell damage:
 * Incoming Spell Damage Manipulation: :
 * Outgoing Spell Damage Manipulation: :, : , : -






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

Example 3: Generic Damage Manipulation

 * from the previous example instead chooses to cast his on a  with level 4 . Assuming all other modifiers are the same, how much spell damage will be dealt to  (before magic resistance).
 * Dispersion is generic damage manipulation, meaning it affects all damage dealt to . Despite this, it stacks additively with other incoming spell damage manipulation like when calculating spell damage.
 * spell damage:
 * Incoming Spell Damage Manipulation: :
 * Incoming Generic Damage Manipulation: : -
 * Outgoing Spell Damage Manipulation: :, : , : -






 * affected by will take spell damage (before magic resistance) from  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.



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.



For -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.

Exceptions
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 not affected by outgoing spell damage amplification, but they are affected some sources of incoming spell damage amplification (e.g. ):

Patch History
Dano mágico Урон от заклинаний 技能伤害