View source for XP Formula Library

Formulas are Ruby expressions that are evaluated at run-time. You can use them in damage formulas to determine how much damage you inflict with a skill, or you can use them in script calls to perform certain functions that aren't provided through the event interface by default.

A formula may contain special [[formula variables]] that you can use to craft your formulas.

==Damage Formulas==

Damage formulas by default are used in [[Skills]] and [[Items]], and are primarily used to determine how much base damage the action will inflict.

The following formula variables are available:

* a - user of the action
* b - target of the action
* v - game variables (equivalent to $game_variables)

===Common XP Formulas===

====Normal Attacks====
Power = a.atk - (b.def / 2)
Rate = 20 + a.str
Variance = 15
Minimum power = 0

====Skills====
'''If Skill Power is positive:'''
Power = (a.atk x skill.atkFactor / 100) - (b.def x skill.defFactor / 200) - (b.mdf x skill.mdfFactor / 200)
Variance = skill.variance
Minimum power = 0

'''If Skill's Power is negative:'''
Power = 20 + (a.str x skill.strFactor / 100) + (a.dex x skill.dexFactor / 100) + (a.agi x skill.agiFactor / 100) + (a.int x skill.intFactor / 100)
Variance = skill.variance

====Items====
'''HP recovery amount is negative:'''
Power = -Amount HP Recovered - (b.def x item.defFactor / 20) - (b.mdf x item.mdfFactor / 20)
Variance = item.variance
Minimum power = 0

'''HP recovery amount is positive:'''
Power = -Amount of HP recovered
Variance = item.variance
Minimum power = 0

Damage = power x multiplier / 20 x elemental modifier x critical modifier x defense modifier (+- variance %)

Elemental modifier: The weakest of b's effective elements corresponding to the action's element (s).
[A: 200%, B: 150%, C: 100%, D:50%, E: 0%, F: -100%]
Critical modifier: Equals 2 when the damage is positive and a critical hit is made.
Defense modifier: Equals 1/2 when the damage is positive and b is defending.

==Hit Formula==
Hit formulas by default are used in [[Skills]], and are primarily used to determine whether an attack hits successfully or not.  In XP, "to hit" is split into:
*First Hit
*Is Critical Hit?
*Second Hit

===Common XP Formulas===
====First Hit====
'''Normal Attacks''': First hit rate = a.state.hitRate
'''Skills If Attack Power F is 1 or greater (physical attack)''': First hit rate = skill.hitRate x a.state.hitRate / 100
'''Skills If Attack Power F is 0 (non-physical attack)''': First hit rate = skill.hitRate
'''Items''': First hit rate = item.hitRate

If a's condition is normal, the state hit rate is 100.

====Is Critical Hit?====
'''Normal Attacks''': Critical hit rate = 4 x a.dex / b.agi
'''Skills''': Critical hit rate = 0
'''Items''': Critical hit rate = 0

====Second Hit====
If damage is negative, second hit rate = 100%

'''If damage is positive:'''
'''If b's condition is normal:'''
evasion = 8 x b.agi / a.dex + b.evade

'''Normal attacks''': Second hit rate = 100 - evasion
'''Skills''': Second hit rate = 100 - (evasion x skill.evasionF / 100)
'''Items''': Second hit rate = 100%

==Escape Formula==
Determines whether an escape attempt is successful or not.

===Common XP Formulas===
Successful escape rate = 50 x playerParty.avgAgi / monsterTroop.avgAgi

==Related Topics==
* [[Dungeons and Dragons Engine/D&D Damage Formulas|D&D Damage Formulas]]
* [[MV Formula Library]]
* [[VX Formula Library]]

==Sources==
* RPGMaker XP Product Documentation (Enterbrain)