Damage modifier

References

1. ^ abcdWhen the weapon's type bonus matches the target's type, or the weapon's element matches one of the target's weak elements, the attack power gains 20 before the damage is rolled.Codeeverything8215, FF2 disassembly
   How we know

   163320C/B086: B1 9F     LDA ($9F),Y        ; main hand attack power
   ⋮
   163370C/B090: B1 9F     LDA ($9F),Y        ; main hand type bonus
   163380C/B092: A0 15     LDY #$15
   163390C/B094: 31 A1     AND ($A1),Y        ; target type
   163400C/B096: D0 0A     BNE $B0A2
   163410C/B098: A0 1B     LDY #$1B
   163420C/B09A: B1 9F     LDA ($9F),Y        ; main hand element
   163430C/B09C: A0 16     LDY #$16
   163440C/B09E: 31 A1     AND ($A1),Y        ; target weak elements
   163450C/B0A0: F0 0D     BEQ $B0AF
   163460C/B0A2: 18        CLC 
   163470C/B0A3: A5 44     LDA $44
   ⋮
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

2. ^ abcA resisted element halves a damage spell's power and drops the 148 from its doubling chance; a weakness multiplies the power by 1.5 and adds 40 to the chance.CodeDisch, FF1 disassembly
   How we know

   8289    AND btlmag_defender_elemresist          ; see if the defender resists this element
   ⋮
   8291      JSR BtlMag_ZeroHitChance              ; ... zero the hit/crit chance
   8292      LSR math_basedamage+1                 ; and halve the damage
   ⋮
   8296    AND btlmag_defender_elemweakness        ; see if they are weak to the element
   ⋮
   8300      JSR MathBuf_Add                       ; crit bonus of +40
   ⋮
   8302                                            ; damage *= 1.5
   

   Checked against the evidence by its author, an AI model, 2026-10-20.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

3. ^ abcdeA critical hit doubles the level in the damage formula and takes both Pokémon's stats from their party data, so stat stages, Reflect, and Light Screen drop out.Codepret/pokered
   How we know

   4056	ld a, [wCriticalHitOrOHKO]
   4057	and a ; check for critical hit
   4058	jr z, .scaleStats
   4059; in the case of a critical hit, reset the player's attack and the enemy's defense to their base values
   4060	ld c, STAT_DEFENSE
   4061	call GetEnemyMonStat
   

   4131	ld a, [wBattleMonLevel]
   4132	ld e, a ; e = level
   4133	ld a, [wCriticalHitOrOHKO]
   4134	and a ; check for critical hit
   4135	jr z, .done
   4136	sla e ; double level if it was a critical hit
   

   Checked against the evidence by its author, an AI model, 2026-10-20.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

4. ^ abEach hit that gets through deals attack plus a random 0 to attack, less the target's defense (at least 0), and the hits add up. Each hit also rolls 0–100, and a roll under 5 makes it critical, adding the attack again.Codeeverything8215, FF2 disassembly
   How we know

   18008; [ calculate damage ]
   ⋮
   18010;  $44: attack
   18011;  $46: defense
   18012;  $48: number of hits
   18013; +$4A: damage
   ⋮
   18030; start of hit loop
   180310C/BCA7: A2 00     LDX #$00
   180320C/BCA9: A5 44     LDA $44
   180330C/BCAB: 20 11 FD  JSR $FD11          ; random (X..A)
   180340C/BCAE: 18        CLC 
   180350C/BCAF: 65 44     ADC $44            ; attack * (0..1)
   ⋮
   180410C/BCBA: A5 4C     LDA $4C            ; subtract defense
   ⋮
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

5. ^A damage spell always connects, for a random value from its power $E$ to $2E$; its roll of 0–200 against 148 + the spell's hit rate − the target's magic defense doubles the damage instead of deciding a hit.CodeDisch, FF1 disassembly
   How we know

   8284    JSR BtlMag_MarkSpellConnected           ; damage spells always connect
   8285    JSR BtlMag_LoadBaseHitChance            ; load base hit chance (since damage always hits, this becomes more of a "critical" chance)
   

   8208    LDA #<148               ; base hit chance of 148
   

   8156    JSR MathBuf_Add             ; math_hitchance += spell's base hit rate
   ⋮
   8160    JSR MathBuf_Sub             ; math_hitchance -= defender's magdef
   ⋮
   8168    JSR MathBuf_Add             ; math_basedamage = rand[ spelldamage, spelldamage*2 ]
   

   8328    BEQ :+                          ; if the hit/crit roll was 200, this is NOT a crit
   ⋮
   8331        ASL math_basedamage         ; ... do 2x damage
   

   Checked against the evidence by its author, an AI model, 2026-10-20.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

6. ^ abcAdjustDamageForMoveType applies STAB before any type row: $\mathrm{damage}+\lfloor \mathrm{damage}/2\rfloor$ when the move's type matches either attacker type.Codepret/pokered
   How we know

   5116	srl b
   5117	rr c      ; bc = floor(0.5 * damage)
   5118	add hl, bc ; hl = floor(1.5 * damage)
   

   Checked against the evidence by its author, an AI model, 2026-10-20.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

7. ^ abcA swing is critical when its roll is at most the crit chance, which is capped at the hit chance; a critical adds the swing's random damage again, with no absorb taken from it.CodeDisch, FF1 disassembly
   How we know

   4404      LDA math_hitchance                ; crit chance cannot exceed hit chance
   

   4515    LDA math_critchance     ; see if hit value is <= crit chance  (this will be impossible if the attack was a miss)
   ⋮
   4519      LDX math_basedamage                   ; add random damage to our total
   4520      JSR MathBuf_Add
   4521      INC battle_critsconnected
   

   Checked against the evidence by its author, an AI model, 2026-10-20.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

8. ^ abIn table order, each TypeEffects row matching the move's type and either defender type sets damage to $\lfloor \mathrm{damage}\times \mathrm{value}/10\rfloor$; 0 marks a miss.Codepret/pokered
   How we know

   5161	call Multiply
   5162	ld a, 10
   5163	ldh [hDivisor], a
   5164	ld b, 4
   5165	call Divide
   

   Checked against the evidence by its author, an AI model, 2026-10-20.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

9. ^In the North American build, damage is attack less defense, where attack is the weapon's might plus the triangle's damage bonus, tripled when the attacker or its weapon is effective against the target (doubled instead when the effective weapon is one of eight legendary weapons), plus the attacker's strength, and defense is terrain defense plus Defense, or terrain resistance plus Resistance against magic; no roll changes it except two skills, Pierce (which sets defense to 0) and Great Shield (which sets the damage to 0); a critical triples it, and the result is held within 0–127.Codefireemblem8urevised
   How we know

   512    if (GetItemAttributes(defender->weapon) & IA_MAGICDAMAGE)
   513        attacker->battleDefense = attacker->terrainResistance + attacker->unit.res;
   ⋮
   515        attacker->battleDefense = attacker->terrainResistance + attacker->unit.res;
   ⋮
   517        attacker->battleDefense = attacker->terrainDefense + attacker->unit.def;
   

   527    attacker->battleAttack = GetItemMight(attacker->weapon) + attacker->wTriangleDmgBonus;
   ⋮
   530    if (IsUnitEffectiveAgainst(&attacker->unit, &defender->unit) == TRUE)
   531        attack = attacker->battleAttack * 3;
   ⋮
   533    if (IsItemEffectiveAgainst(attacker->weapon, &defender->unit) == TRUE) {
   ⋮
   538        case ITEM_SWORD_AUDHULMA:
   ⋮
   545        case ITEM_LANCE_SIEGMUND:
   546            attack *= 2;
   ⋮
   549        default:
   550            attack *= 3;
   ⋮
   556    attacker->battleAttack = attack;
   557    attacker->battleAttack += attacker->unit.pow;
   

   1022    if (gBattleHitIterator->attributes & BATTLE_HIT_ATTR_PIERCE)
   1023        defense = 0;
   ⋮
   1025    gBattleStats.damage = attack - defense;
   ⋮
   1027    if (gBattleHitIterator->attributes & BATTLE_HIT_ATTR_GREATSHLD)
   1028        gBattleStats.damage = 0;
   

   1030    if (BattleRoll1RN(gBattleStats.critRate, FALSE) == TRUE) {
   ⋮
   1039            gBattleStats.damage = gBattleStats.damage * 3;
   

   1043    if (gBattleStats.damage > BATTLE_MAX_DAMAGE)
   1044        gBattleStats.damage = BATTLE_MAX_DAMAGE;
   ⋮
   1046    if (gBattleStats.damage < 0)
   1047        gBattleStats.damage = 0;
   

   16    // Maximum battle damage
   17    BATTLE_MAX_DAMAGE = 127,
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Revised after a check by a second AI model, 2026-10-21.

   In the claim ledger

10. ^ abCmd_damagecalc multiplies the base damage by 2 on a critical; CalculateBaseDamage then ignores the attacker's lowered attacking stat, the defender's raised defending stat, and Reflect or Light Screen.Codepret/pokeemerald
    How we know

    1296    gBattleMoveDamage = gBattleMoveDamage * gCritMultiplier * gBattleScripting.dmgMultiplier;
    

    3234        if (gCritMultiplier == 2)
    ⋮
    3236            // Critical hit, if attacker has lost attack stat stages then ignore stat drop
    ⋮
    3248        if (gCritMultiplier == 2)
    ⋮
    3250            // Critical hit, if defender has gained defense stat stages then ignore stat increase
    ⋮
    3267        if ((sideStatus & SIDE_STATUS_REFLECT) && gCritMultiplier == 1)
    

    Checked against the evidence by its author, an AI model, 2026-10-20.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

11. ^In the North American build, a unit's crit is its weapon's crit plus half its skill, plus 15 for classes with a crit bonus; the crit shown and rolled is that less the defender's luck, at least 0, and one random number from 0 to 99 below it triples the hit's damage.Codefireemblem8u
    How we know

    589    bu->battleCritRate = GetItemCrit(bu->weapon) + (bu->unit.skl / 2);
    ⋮
    591    if (UNIT_CATTRIBUTES(&bu->unit) & CA_CRITBONUS)
    592        bu->battleCritRate += 15;
    ⋮
    596    bu->battleDodgeRate = bu->unit.lck;
    

    612    attacker->battleEffectiveCritRate = attacker->battleCritRate - defender->battleDodgeRate;
    ⋮
    615        attacker->battleEffectiveCritRate = 0;
    ⋮
    617    if (attacker->battleEffectiveCritRate < 0)
    618        attacker->battleEffectiveCritRate = 0;
    

    85s8 Roll1RN(int threshold) {
    86    return (threshold > NextRN_100());
    

    1030    if (BattleRoll1RN(gBattleStats.critRate, FALSE) == TRUE) {
    ⋮
    1038            gBattleHitIterator->attributes = gBattleHitIterator->attributes | BATTLE_HIT_ATTR_CRIT;
    1039            gBattleStats.damage = gBattleStats.damage * 3;
    

    883    gBattleStats.critRate = attacker->battleEffectiveCritRate;
    

    243    critRate = gBattleActor.battleEffectiveCritRate;
    

    Checked against the evidence by its author, an AI model, 2026-10-21.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

12. ^In Red and Blue, a damaging move runs CriticalHitTest, CalculateDamage (base formula), AdjustDamageForMoveType (STAB, then type rows), RandomizeDamage, and then MoveHitTest (accuracy).Codepret/pokered
    How we know

    3144	call CalculateDamage
    ⋮
    3147	call AdjustDamageForMoveType
    3148	call RandomizeDamage
    3149.moveHitTest
    3150	call MoveHitTest
    

    Checked against the evidence by its author, an AI model, 2026-10-20.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

13. ^Truncating after each row can cost a hit that nets ×1 damage when its ½ row comes first: Ice against Water/Flying takes 3 to ⌊3 × 5 / 10⌋ = 1, then ⌊1 × 20 / 10⌋ = 2, not 3.Codepret/pokeredrevised
    How we know

    33	db ICE,          WATER,        NOT_VERY_EFFECTIVE
    ⋮
    36	db ICE,          FLYING,       SUPER_EFFECTIVE
    

    Measured by a script. It fails if the result disagrees with the claim.

    Checked against the evidence by its author, an AI model, 2026-10-20.

    Revised after a check by a second AI model, 2026-10-21.

    In the claim ledger

14. ^A plain damaging move runs critcalc, damagecalc (base damage), typecalc (STAB, then type rows), and then adjustnormaldamage (random factor).Codepret/pokeemerald
    How we know

    249	critcalc
    250	damagecalc
    251	typecalc
    252	adjustnormaldamage
    

    Checked against the evidence by its author, an AI model, 2026-10-20.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

15. ^Before the type chart, Cmd_typecalc applies STAB as $\mathrm{damage}\times 15/10$ when either attacker type equals the move's type.Codepret/pokeemerald
    How we know

    1368    // check stab
    1369    if (IS_BATTLER_OF_TYPE(gBattlerAttacker, moveType))
    ⋮
    1371        gBattleMoveDamage = gBattleMoveDamage * 15;
    1372        gBattleMoveDamage = gBattleMoveDamage / 10;
    

    Checked against the evidence by its author, an AI model, 2026-10-20.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

16. ^For each row of the move's type, ModulateDmgByType runs once per distinct target type it matches: $\mathrm{damage}\times \mathrm{multiplier}/10$, raised from 0 to 1 unless the multiplier is 0.Codepret/pokeemerald
    How we know

    1323    gBattleMoveDamage = gBattleMoveDamage * multiplier / 10;
    1324    if (gBattleMoveDamage == 0 && multiplier != 0)
    1325        gBattleMoveDamage = 1;
    

    1401                if (TYPE_EFFECT_DEF_TYPE(i) == gBattleMons[gBattlerTarget].types[1] &&
    1402                    gBattleMons[gBattlerTarget].types[0] != gBattleMons[gBattlerTarget].types[1])
    

    Checked against the evidence by its author, an AI model, 2026-10-20.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger