Stacking[ | ]
In general, status effects do not stack, and anything that is not a status effect stacks unless explicitly stated otherwise (such as in 
Heavy Blade 3). Some skills stack in straightforward ways (e.g. simple addition using two 
Attack +3 or two 
Darting Blow 3) while some skills stack in ways that are not obvious, such as multiplicative effects (
Urvan), or follow-up interactions which is described later.
Stacking stat increases[ | ]
Bonuses are temporary beneficial status effects. For example 
Rally Attack is an assist skill that gives a unit a status increase of +4 Atk for a round. 
Penalties are the reverse from bonuses and cause detrimental status effects to a unit.
There is a way to identify which stat increases and decreases do and do not stack. To simplify the following sections, only positive increases will be used. Since status effects all follow the same stacking rules, the rest of this section will refer only to bonuses but still applies to penalties as well. Likewise, everything referring to a boost applies to reductions as well.
- Bonuses: The activation of these bonuses occur outside combat. These status effects are visible when a player selects their unit. A net positive in stats will highlight the stat in blue while a net negative will show the stat in red. Skills that fall under this category include:
- Assist skills (e.g. Rally skills)
- Hone/Fortify skills
- Defiant skills
- Certain weapon effects similar to the aforementioned skills (e.g.
Rogue Dagger+).
- In general, look for skills that say they grant a stat for 1 turn (although technically the statement is false, as bonuses last until the start of the unit's phase, not for exactly 1 turn).
- Combat boosts: These stat increases only affect a Hero in combat. These gained stats will not be visible in the hero status screen (because that is outside combat), but will affect the combat forecast. Typically the description of these skills will include the phrase "during combat". Examples of skills that fall under this category include:
For bonuses, any bonus which affects the same stat will not stack with each other (e.g. Rally Attack and 
Hone Atk 4). Only the bonus with the highest stat increase will apply. Bonuses affecting different stats (e.g. Rally Attack and 
Hone Spd 3) will not affect each other, as they affect different stats.
For combat boosts, all combat boosts will stack with each other with no upper limit.
Both bonuses and combat boosts will stack with each other, as well as non-combat boosts.
These rules also apply to penalties. Additionally, bonuses and penalties both apply at the same time and will not cancel each other out. Their interaction with each other is calculated before being applied to Heroes.
Skill interactions[ | ]
There are many skills with different effects and some of them will have contradicting effects to each other when they interact. The following tables note some such interactions.
When two skills with contradictory effects interact, the contradictory effects cancel out, but the remaining conditions and effects are still active. A skill can only cancel out one other skill, for example, if there is one skill that has a "yes" effect and two skills that has a "no" effect, one "yes" effect and one "no" effect will cancel out, but the remaining "no" effect will still be active. Note that skills that disable another skill do not interact this way, since they do not have contradictory effects. For example, an active desperation effect from a 
Starfish+ and another active 
Desperation 3 effect will not cancel out with 
Hardy Bearing 3.
Follow-up attacks[ | ]
Some skills can grant or deny the ability to perform a follow-up attack.
| Guaranteed follow-up attack | Prevent follow-up attack | |
|---|---|---|
| Self | ||
| Foe |
When the "no follow-up attacks" and "guaranteed follow-up attacks" effects cancel out, a standard speed check decides follow-up attacks.
| Unit 1 | Unit 2 | Results |
|---|---|---|
|
|
All effects of both of the skills will cancel each other out; a standard speed check (≥5 Spd) determines follow-up attacks for both units. For an example, this scenario can be achieved by having two sword users use  Swordbreaker 3 against each other.
|
|
|
Unit 2 will be unable to perform a follow-up attack on unit 1. A standard speed check (≥5 Spd) determines follow-up attacks for Unit 1. An example of this scenario is a unit using  Lancebreaker 3 against a lance user with  Wary Fighter 3.
|
|
|
Unit 1 will perform a follow-up attack regardless of speed. A standard speed check (≥5 Spd) determines follow-up attacks for Unit 2. An example of this scenario is a unit using  Axebreaker 3 against an axe user with  Quick Riposte 3.
|
|
|
Unit 1 will perform a follow-up attack regardless of speed. Unit 2 will perform a follow-up attack regardless of speed. An example of this scenario occurring would be a unit using  R Tomebreaker 3 against a red tome user using two Quick Riposte 3 skills.
|
| These interactions can continue for any number of effects that prevent or guarantee follow-up attacks. The way contradictory effects cancel out can be used to understand any number of these effects interacting with each other.
Note that remaining conditions and effects are still active, so Special cooldown charge would still be in play for a |
Attacking twice[ | ]
Examples of skills which allow a unit to attack twice are 
Brave Sword+ or Meisterschwert.
| Unit | Results |
|---|---|
|
The unit attacks twice in combat. For example, if they initiate combat, the attacking order is Unit → Unit → Foe. If the foe initiates combat, the attacking order is Foe → Unit → Unit. (Note that most weapons grant "attacks twice" only when unit initiates combat). |
|
The unit attacks twice in combat. For every follow-up attack they make, they attack twice. If they initiate combat, the attacking order is Unit → Unit → Foe → Unit → Unit. If the foe initiates combat (or this unit initiates, but the foe moves first by Vantage or skill granting it), the attacking order is Foe → Unit → Unit → Unit → Unit. |
|
The unit attacks twice in combat. Preventing follow-up attacks does not prevent a unit from attacking twice, as they are different effects. |
Weapon-triangle[ | ]
Before continuing, some terms will be defined. Weapon-triangle advantage/disadvantage itself is the normal ±20% that colored weapon users have granted by default against their opponent color. Weapon-triangle advantage can be granted by skills as well. Affinity is different, and enhances the effect of the regular weapon-triangle advantage. It can be thought of as the intensification of the weapon-triangle, rather than the weapon-triangle advantage/disadvantage itself.
Examples of skills that grant weapon-triangle advantage are 
Gronnraven+, while examples of skills that grant affinity are 
Triangle Adept 3 or Ruby Sword+.
Cancel Affinity is described in detail, as it is a common source of confusion.
| Unit 1 | Unit 2 | Results |
|---|---|---|
| Combat proceeds with the weapon-triangle being ±40%, ±20% from normal and ±20% from the skill. | ||
| Affinity does not stack (only highest value is applied) and combat proceeds with the weapon-triangle being ±40%. | ||
| Affinity does not stack (only highest value is applied) and combat proceeds with the weapon-triangle being ±40%. | ||
| Triangle Adept's effects will be ignored, and the battle will continue on as if the skill did not exist. Regular weapon triangle advantages and disadvantages will still exist. | ||
| If the Cancel Affinity user is at a weapon triangle disadvantage against the Triangle Adept user (e.g. Blue CA vs. Green TA), Triangle Adept's affinity is disabled. Triangle Adept's effects will be ignored if the Cancel Affinity user is at a weapon triangle disadvantage, but not ignored if the Cancel Affinity user is at a weapon triangle advantage. | ||
If the Cancel Affinity user is at a weapon triangle disadvantage against the Triangle Adept user (e.g. Blue CA vs. Green TA), Triangle Adept's Atk affinity is reversed and subtracted from the normal 20% gained from weapon triangle advantage. This results in:
| ||
| Cancel Affinity does not affect -raven Tomes when Triangle Adept is not equipped, as -raven Tomes do not enhance an existing triangle advantage but rather inserts a new triangle advantage. | ||
| Cancel Affinity does not affect the base 20% advantage granted by -raven Tomes, but, depending on the level of Cancel Affinity, a certain amount of the added advantage from Triangle Adept will be negated or reversed. |
Example interactions with a blue lance unit attacking   
| ||||
|---|---|---|---|---|
Versus  Azura: Lady of Ballads ( Axe, Weapon disadvantage)
| ||||
| Azura with no Triangle Adept | Azura with  Triangle Adept 1 |
Azura with  Triangle Adept 2 |
Azura with Triangle Adept 3
| |
| Mathilda with no Cancel Affinity | -20% | -30% | -35% | -40% |
Mathilda with  Cancel Affinity 1 |
-20% | -20% | -20% | -20% |
Mathilda with  Cancel Affinity 2 |
-20% | -20% | -20% | -20% |
Mathilda with  Cancel Affinity 3 |
-20% | -10% | -5% | 0% |
Versus  Roy: Young Lion ( Sword, Weapon advantage)
| ||||
| Roy with no Triangle Adept | Roy with Triangle Adept 1 |
Roy with Triangle Adept 2 |
Roy with Triangle Adept 3
| |
| Mathilda with no Cancel Affinity | +20% | +30% | +35% | +40% |
| Mathilda with Cancel Affinity 1 |
+20% | +20% | +20% | +20% |
| Mathilda with Cancel Affinity 2 |
+20% | +30% | +35% | +40% |
| Mathilda with Cancel Affinity 3 |
+20% | +30% | +35% | +40% |
Special cooldown charge[ | ]
Every attack a unit makes in combat charges their special. By default, the Special cooldown charge amount is 1. Some skills can grant or inflict additional Special cooldown charges during combat. This is not the same as skills which accelerate or slow the Special trigger.
| Grants (+) | Inflicts (−) | |
|---|---|---|
| Self | ||
| Foe |
As many skill descriptions state, only the highest value is applied of each effect.
| Unit 1 | Unit 2 | Unit 1 charge | Unit 2 charge | Results |
|---|---|---|---|---|
| 1 | 1 | With no skills, for each attack for each unit their Special cooldown charge is 1, and their cooldown count is reduced by 1. | ||
|
2 | 1 | Unit 1 will get 2 numbers closer to readying their Special every attack. | |
|
1 | 0 | Unit 1's Special cooldown charge will function as normal. Unit 2's Special cooldown charge is 0, and thus their cooldown counter does not decrease. | |
|
|
2 | 0 | Unit 1 will get 2 numbers closer to readying their Special every attack. Unit 2's Special cooldown charge is 0, and thus their cooldown counter does not decrease. |
|
1 | 1 | Unit 1's cooldown charge functions as normal. | |
|
1 | 1 | The "Special cooldown charge +1" effects do not stack, and only the highest value is treated as applied. Thus the interaction becomes only one "Special cooldown charge +1" and one "Special cooldown charge -1" effect interacting. The next example will also explain this with a more specific example. | |
|
- | Reminder: Both Heavy Blade and Bold Fighter only activate the "cooldown charge +1" effect on the unit's attacks, and are not active on the foe's attack, as per the skill descriptions.
If Unit 1 initiates combat: Unit 1's cooldown count lowers by 1 for their attacks (the regular cooldown charge), and receives no change to their cooldown count for Unit 2's attacks.[1] If Unit 2 initiates combat: Units 1's cooldown count lowers by 1 for their attacks, and receives no change to their cooldown count for Unit 2's attacks.[2] The interactions play out as if Bold Fighter did not exist, because "Special cooldown charge +" effects do not stack, only the highest value is treated as being applied. | ||
Special[ | ]
| Unit 1 | Unit 2 | Results |
|---|---|---|
| — | The added damage will affect all enemies the AoE special damages. | |
| — | Skills that target the lower defensive stat will be taken into account when using AoE Specials. | |
| — | The offensive special trigger-based skill will not add any damage if used with a defensive special. | |
If used against a special, the +10 damage effect of Wo Dao+ for example, will be counted in being reduced by  Pavise.
| ||
| — | The damage from the AoE Special will not trigger the healing from Solar Brace. | |
|
The counterattack will not have its damage dealt reduced due to Aegis and similar skills requiring the foe to be 2 spaces away instead of having Range = 2, despite the English description.
| |
|
Unit 1 survives with 1 HP. Miracle remains ready.
|
Bonuses and penalties[ | ]
In general, skills affecting bonuses and penalties only consider the highest valued one. Ploy skills are not affected by combat boosts.
| Unit 1 | Unit 2 | Results |
|---|---|---|
|
— | Only the highest amount of each stat decrease will apply.
Only Seal Def will apply if the user cannot attack and survives combat, due to differing activation requirements. |
|
— | Harsh Command does not affect the panic status effect. Harsh Command does not apply to bonuses affected by the panic status effect.
If there is only bonuses reversed by Panic on the target unit, Harsh Command cannot be used. If a target unit has regular penalties, convert penalties to bonuses as usual. The resultant bonuses on target is still subject to panic status. |
|
|
If these two skills activate at the same time (e.g. both "at start of turn"), stat thresholds checked before stat changes applied. For example, skills with an HP requirement check will check those requirements first, and then healing will occur after. Thus, a Hero at 99% HP and with  Renewal 3 and  Armored Boots will not be granted the +1 movement that turn. The exception to this rule is  Prayer Wheel, which had its intended behavior changed.
|
| — | Penalties and reversed buffs do not increase nor decrease the damage dealt. | |
| Blizzard
|
 Panic
|
The reversed bonuses are treated as penalties. |
| Restore+
|
Panic
|
The reversed bonuses are reverted to normal, alongside actual penalties being removed. |
|
Bonus neutralization skills target unreversed bonuses, and thus don't negate the reversed ones. | |
|
— | Unit 2's bonuses are not counted when adding stats. Unit 2's bonuses are neutralized and treated as if they do not exist. Dull Ranged results in The Cleaner+ not granting extra Atk. |
|
|
Unit 2's penalties are not counted when adding stats. Unit 2's penalties are neutralized and treated as if they do not exist. Demonic Breath results in Blizzard not granting extra Atk.[3] |
|
|
|
|
— | All these effects will stack, and Unit 1 will have its special count reduced by 3. |
| Various Garm interactions
|
Penalties do not affect Garm's guaranteed follow-up attack. If a unit has both bonuses and penalties, the guaranteed follow-up attack will activate.[4] Skills that neutralize bonuses will remove Garm's guaranteed follow-up attack.[5] If the unit is inflicted with Panic and unit has bonuses, Garm's follow-up will be ignored.[6]
| |
Movement[ | ]
| Unit 1 | Unit 2 | Results |
|---|---|---|
| The unit can move only one space. Gravity sets movement to 1 while skills like Armored Boots increases movement by 1. | ||
| Gravity has no effect on movement through warp skills. | ||
| Obstruct has no effect on movement through warp skills. | ||
| Obstruct has no effect on movement through assist skills. |
Combat[ | ]
During combat, skills that are only active during combat are evaluated in this order:
- Skills that grant combat boosts
- Skills that grant combat boosts are evaluated in the following order:
- Player unit's skills
- Skill slot order
- Enemy unit's skills
- Skill slot order
- Player unit's skills
- Skills that grant combat boosts are evaluated in the following order:
- Skills that do not grant combat boosts
- Skill slot order
Skill slot order is as follows:
- Weapon
- Assist
- Special
- Passive A
- Passive B
- Passive C
- Sacred Seal
- Refined skill effect of weapons
The order of skill evaluation is largely trivial, and only comes into play when there are skills that check a unit's stats during combat.
There appear to be two methods which skills can use to check stats during combat:
- Stat check: The simplest method where skills just check the latest value and use it. Skills like Heavy Blade 3 use this method. However, currently no skill exists that uses this check and can grant combat boosts.
- Outside stats: Method where skills take the stats before combat was entered. Typically Sagittae and other skills that both grant and check stats use this method.
| Unit 1 | Unit 2 | Results |
|---|---|---|
|
|
Unit 1 will get the +6 Speed from Darting Blow 3 before Windsweep checks Spd. Windsweep's Spd requirement is fulfilled. |
|
|
Unit 1 gets both the Atk/Spd+7 from Brazen and the Atk/Spd/Def/Res+5 from Sagittae. |
Outside combat[ | ]
- When a skill has a targeting condition where multiple units are eligible/tied, such as Chill Atk 3, Kriemhild, Sökkvabekkr, Sparkling Boost, all units will be selected. For example, Sparkling Boost will restore HP for all allies if they all have taken exactly 7 damage.
| Unit 1 | Unit 2 | Results |
|---|---|---|
|
The damage from Savage Blow and Breath of Life will occur before displacement. | |
|
The damage and displacement from the Umbra Specials will occur after Unit 1's displacement. | |
| They both stack with each other. | ||
| Both apply. | ||
| They both stack with each other. | ||
| They both stack with each other. | ||
|
They both stack with each other. | |
| They stack with each other; in addition to healing half the health missing from the healer, they also gain a percentage of what the ally is healed. | ||
| They do not stack with each other and only the higher amount will apply. | ||
|
The healing or damage will apply before Bunny Fang performs its HP check.
| |
| The damage from the Umbra Specials will apply after Bunny Fang performs its HP check.
|
Other[ | ]
| Unit 1 | Unit 2 | Results |
|---|---|---|
|
|
The damage mitigation effect of damage-reducing skill effects does stack (albeit multiplicatively). For example, two consecutive hits for 19 damage will do 19 and 4 damage respectively with just Urvan, but with both Urvan and the  Deflect Melee 1 the second hit will do 3 damage instead.
Examples of skills with damage-reducing skill effects are: |
|
— | Unit will attack twice when activating Vantage. |
|
— | Guaranteed follow-up attacks on skills will work with Desperation, and will happen immediately as well. |
| — | Windsweep disables follow-up attacks when initiating, but when fighting a  Colorless Dagger user, Assassin's Bow's Daggerbreaker effect grants a guaranteed follow-up. These effects cancel each other out, and the regular speed check applies when determining follow-up attacks. The dagger unit cannot counterattack if Windsweep's sweep condition is fulfilled (Spd ≥ 1). If the dagger unit can counterattack, they cannot perform a follow-up attack due to Assassin's Bow's remaining effect.
| |
| — | Brash Assault will have no effect if Windsweep successfully activates due to its conditions. Brash Assault will only work if the enemy can counterattack. | |
| — | When unit 1 initiates combat, unit 2 cannot counterattack.[7]
When unit 2 initiates combat, unit 1 can counterattack.[7] |
References[ | ]
- ↑ Media:Skill_Interaction_Heavy_Blade_Bold_Fighter_Unit_Initiates.webm
- ↑ Media:Skill_Interaction_Heavy_Blade_Bold_Fighter_Foe_Initiates.webm
- ↑ Media:Skill_Interaction_PenaltiesToAtk_PenaltyNeutralization.png. If penalties were counted, 3 damage for each attack would have been done.
- ↑ https://i.imgur.com/Cfadcz9.mp4
- ↑ https://i.imgur.com/N22h0E4.mp4
- ↑ https://i.imgur.com/rm7PHhs.mp4
- ↑ 7.0 7.1 https://www.reddit.com/r/FireEmblemHeroes/comments/aeqbtp/null_cdisrupt_and_firesweep_interaction/
