This guide covers in-battle stat changes, and not skills that change the base stats of a unit such as Fury and Speed + 3.
There are two types of in-battle stat changes:
- visible ones, which include buffs and debuffs
- in-combat buffs granted by allied area of effect
They exist independently until they are checked for calcs or comparisons. Since buffs and debuffs skills affect units around their user, they are most often C skills. HP cannot be modified. All buff/debuff values given account for the highest level of the skill. Listed weapons are non-exhaustive.
When you tap a unit's stat above the battle map or on the unit's screen (accessed by long-pressing the unit of your choice), visible buffs are shown in blue and visible debuffs in red. Their sum's color is then reflected on the stats summary. Visible buffs and debuffs only take the highest-value each and do not stack. eg using Rally Atk and Rally Atk/Spd will give +4 Atk and +3 Spd.
Rally skills are active support skills that spend a unit's turn. Basic rallies buff for +4. Double rallies buff for +3 in two stats.
Hone and Fortify X stat give +4 in the given stat to adjacent allies at the start of the turn.
Hone and Fortify X type of unit give +6 in either atk/spd or def/res to a unit of the corresponding type, making themed teams popular.
Defiant X stat are self-boosting A-slot skills. At the start of the turn, the game checks if the user's current HP is equal or less than half of his max HP. If it is the case, a buff of +7 is granted.
Refreshing units (who have Dance or Sing as their support skill) may learn a B slot skill such as Gale Dance that gives a buff after the refreshing skill is used. The limited unit Performing Azura's weapon Urdr has a +3 to all stats effect.
Daggers and some staves have a post-battle debuffing effect as long as they hit the enemy. The Rogue Dagger even buffs its user at the same time.
Seal skills are B slot skills that affect the enemy post-battle. Single-stat seals debuff by -7 and double-stat ones debuff by -5.
Smoke skills and the Smoke Dagger are area of effect (aoe) debuffs. They do not affect the target unit but every enemy in a range of two tiles around it. Smoke skills debuff by -7.
Threaten X stat act in a range of 2 tiles around their user at the start of the turn. Threaten skills debuff by -5.
X stat Ploy skills check for the user's resistance and compares it to every enemy's if they are in the same row or column as the user. Fortify skills act after the Ploy skill so the check is done with your untouched resistance stat. Ploy skills debuf by -5.
Skills and weapons ignoring enemy visible buffs
At the time of writing, there are three units able to ignore visible buffs.
Status conditions affecting buffs and debuffs
Buffs and debuffs are counted as separate for a reason : there are status conditions that reverse their effects.
Harsh Command is a support skill that changes debuffs into buffs. Example giving, a unit under Seal Atk 3 and Rally Atk would have:
-7 +4 = -3 Atk
Then after an ally uses Harsh Command on them they would have:
+7 +4 = +11 Atk
However, Harsh Command is situational thus rarely used in competitive play. Harsh Command does not reverse the Panic status.
Panic is a status condition primarily inflicted by the Panic staff and the Panic Ploy skill. It changes buffs into debuffs. Contrary to Stat Ploys, Panic Ploy compares HP to apply its effect. It is also available as a Sacred Seal, which makes it widespread. Panic is a popular way to counter Blade tome mages and magical-oriented themed teams such as Horse Emblem.
In-combat buffs do not appear on the battle map. They are Area of Effect (AoE) around their user and are accounted for in the combat forecast and during the combat (Duh.) Unlike visible buffs and debuffs, they are stackable.
In-combat buffing skills
Spur skills buff units adjacent to the user for +4 if for a single stat and for +3 if for two stats.
Drive skills buff units within two spaces of the user for +3 in a single stat.
Goad and Ward X unit type give +4 atk/spd or def/res to units of the corresponding type within two spaces of the user.
Ally Support is like an all-stats Spur and Drive, with the effects being stronger when your pair is adjacent than when they're two spaces away.
Some tome have effects that synergize particularly well with buffs.
Blade tomes stack your “visible” buffs into additional attack buffs. Those buffs mainly come from allied Hone and Fortify skills, and type-based versions are way more potent than the regular versions.
One example: A cavalry blade tome user starting their turn next to a Hone Cavalry user will get +6 (ATK buff) + 6 (blade effect for the ATK buff) + 6 (blade effect for the SPD buff) = 18 additional attack. This goes up to 30 if you have both Hone and Fortify Cavalry applied.
Since Eirika and Ephraim have exclusive weapons with a Hone Atk passive, they are often built with a Rally, a Hone/Fortify and a Fortify Sacred Seal for a all-in-one infantry buffbot package.
Owl tomes and Innes's Nidhogg have the effect of adding +2 to all stats in combat per adjacent ally. Unlike the Blade tomes' strong firepower, Owl tomes provide speed and bulk boosts as well as extra firepower.
Owl tomes have the constraint of requiring adjacent allies (2 are usually enough to give nice buffs) when you combat is expected, versus blade tomes' requirement of having a hone/fortify/rally in your team. However, Owl tomes are not affected by the rise in popularity of Panic Ploy and skills that ignore enemy visible buffs.
Since Owl already requires adjacency, you can use Spur/Goad/Ward skills to their full effect and maintain a close-knit formation.