I have no introduction. I do have math though.

Begin by converting your Weapon's Attack into a "True Weapon Attack" using the formula below
Where "Archetype Modifier" is 0.85 for most archetypes, 0.9 for Prince, and 1.0 for enemies.

also your combined Armor/Gear Defense into a "True Armor Defense" using the formula below

If the skill "Sense of Kinship" is equipped on the attacker, apply one of the below multipliers depending on the number of allies in the same lineage as the attacker, including the attacker themselves. Do the same for "Ironclad Bond" on the defender.


From this point the formula differs depending on if the attacker is a player or an enemy. Note that enemies have equipment just like players do.



Next, True Weapon Attack is turned into "True Attack" by combining it with the skill's power, done as described below.


"Skill Power" is a constant value tied to the skill used in most cases, however there are 2 exceptions

Skills with "Power proportional to caster's remaining HP." have their power multiplied by the attacker's current HP (before paying the HP cost of the skill), then divided by the attacker's max HP.

Lucky Slash has a unique behavior that produces variance. The below values are what Lucky Slash uses, depending on RNG

Meanwhile "Magic Power Factor" is a value determined proportionally to the user's Magic stat. This is only used for skills that scale off Magic, so Strength-based skills use 0 for that value. These are the values used based on the attacker's Magic stat for magic (use the highest one that corresponds to a magic value lower than the attacker's magic)

"True Attack" is then turned into the base "Initial Power" by performing the following operation


Initial Power is set to 10 if it would be a value less than 10.

The next major step is to create a "Stat Multiplier", which is done using the following method
"Attacker Offense" and "Offense Correction" are dependent on what stat the attack scales off of, using the below values


"Raw Damage" when the player attacks is calculated as



Next, True Weapon Attack is turned into "True Attack" by combining it with the skill's power, done as described below.

And then turned into the base "Offense Value" by performing the following operation

"Attacker Offense" is just Strength for basic attacks and physical skills, and Magic for magic skills.

The "Defense Value" used depends on what kind of attack is being used
"Defender Offense" is just Strength for physical skills, and Magic for magic skills.

"Raw Damage" when an enemy attacks is calculated as

A few more "Correction" values are still needed for this step of damage calculation.

"Weakness Correction" is determined by the target's resistance to the attack. The defaults are

However "Resist", "Neutral", and "Weak" can be any number of values for enemies, determined arbitrarily on an enemy-by-enemy and affinity-by-affinity basis, though deviations from the defaults are rare.

"Level Correction" is determined by the difference in level between the attacker and the defender

"Row Correction" is a multiplier specific to whether the attacker is in the front row or back row. Note that enemies are always treated as being in the front row. Row Correction is 1 x the product of all that apply.
*Skill is entirely unused.

"Multihit Correction" is a divisor applied to multihit skills that is simply equal to the skill's highest possible hit count. For example, on a 2-4 hit skill "Multihit Correction" would be 4. On an 8 hit skill "Multihit Correction" would be 8.

The attack's base damage is calculated as

For Plunder Life, which drains HP proportionally to damage dealt, set Base Damage to the target's remaining HP if Base Damage would be higher than it.
Base Damage is set to 1 if it would be a value less than 1.

Once Base Damage has been obtained from the previous section, there's a series of modifiers to apply to it.

Some game mechanics exist that modify damage dealt, those are listed below

The "Difficulty Multiplier" is as follows

The components of which are

The "Buff Multiplier" is as follows

The components of which are

"Ailment Multiplier" is a multiplier to damage dealt or taken that's conditioned on either the Attacker or the Defender having the ailment

"Attack Multiplier" is a multiplier to damage dealt based on a special property of the attack used

The majority of passive skills that modify damage are "Additive" damage boosts. This means that the damage increase is equal to

The following damage increases are additive
*skill is entirely unused

Beyond just the Additive Multiplier, there's a number of passive skills that apply independent multipliers, grouped together as

the below passives are independent multipliers
*skill is entirely unused

To get the actual "Average Damage", combine the multipliers
If Average Damage is 99,999 or greater, the final damage value is set to 99,999.

If Average Damage is 99,998 or less, the next step is to apply damage ranges. This can be any whole % of Average Damage from 95% to 105% (so 95% and 96% are both possible, but 95.5% isn't) selected at random, then rounded down.

Finally, if the final damage value is less than 1, it is instead 1.

It's mentioned in-game that Luck influences the number of times multi-hit skills hit. In actuality the game generates a skip chance using
If Skip Chance would be greater than 10%, it is instead 10%.

Skip Chance is the percentage chance the game skips hit count randomization and gives the max number of hits. If the game randomizes the hit count, then all values from the minimum hit count to the maximum hit count are equally likely.

The vast majority of skills with a random hit count have a range from their minimum hit count to their minimum hit count + 2. For those skills, here's what the odds of each hit count look like based on the value of Skip Chance

The skills Wild Barrage and Wild Salvo instead hit 2-3 times, below is what their odds look like at each Skip Chance

Begin by converting your Weapon's Attack into a "True Weapon Attack" using the formula below
Where "Archetype Modifier" is 0.85 for most archetypes, 0.9 for Prince, and 1.0 for enemies.

If the skill "Sense of Kinship" is equipped on the attacker, apply one of the below multipliers depending on the number of allies in the same lineage as the attacker, including the attacker themselves.


From there the base healing is calculated like this for players

Meanwhile base healing is calculated like this for enemies

"Skill Power" is the power value of the healing skill being used.

"Magic Healing Factor" is a value derived from the skill user's Magic stat, based on the below lookup table (use only the highest applicable one)

Very few multipliers are applied to healing, with only the following to consider

The "Average Healing" is
If Average Healing is 99,999 or greater, the final healing value is set to 99,999 (though this is irrelevant, as there's no method in game to achieve more than 1,305 average healing from a single skill).

If Average Healing is 99,998 or less (which it will be), the next step is to apply damage ranges. This can be any whole % of Average Healing from 95% to 105% (so 95% and 96% are both possible, but 95.5% isn't) selected at random, then rounded down.

Finally, if the final healing value is less than 1, it is instead 1.

The game begins by determining a "Base Accuracy" from the following formula

Evasion being the sum of evasion from Armor and Sub-Armor.
For enemies this is 15 on Fios humans, 20 on Luma humans, 25 on Voidblack Fios humans, and either 0 or 3 in all other cases.

Skill Hit is technically arbitrary on a per-skill basis, however they follow a specific set of rules based on who they target and what stat their damage scales off (note: only reliable for player-usable damaging skills)

with the following exceptions (among player-usable damaging skills)

Several multipliers are applied to Base Accuracy

The "Sukukaja Multiplier" is as follows

The components of which are

The Daze multiplier is set to

There's a number of passive skills that apply multipliers here, grouped together as

the below passives multiply accuracy

There's a few effects beyond multipliers that directly subtract from the final accuracy value, grouped together as

the below effects reduce accuracy

The final Hit Rate is
If Hit Rate would be above 99%, it is instead 99%. If Hit Rate would be below 1%, it is instead 1%.

Lastly, under the following conditions, hit rate calculation is ignored, and a specific result is given

To start, only Strength-based Slash, Pierce, Strike and Almighty attacks can crit.
If the skill can crit, then crit rate is calculated as

"Enemy Penalty" is 0.8 if an Enemy is attacking, and 1.0 if a Player is attacking.

"Skill Crit" is defined arbitrarily per skill. Below is what that value looks like for any (player-usable) skill

The final crit rate is

Where boosts are
*Opening Volley + Stun does not count as an ambush. As a result this is impossible to benefit from as the player. Since no enemies have the skill, this effectively means High Voltage does nothing due to an oversight.

Additionally, under the following circumstances crit rate calculation will either be bypassed, or the result will be ignored (results with "no crit" are prioritized over results with "crit")

The ailment rate formula is

With "Skill Ailment Rate" being defined on a per-skill basis. The following ailment rates are used for players (enemy-only skills may vary from this).

"Weakness Correction" can be any number of values tied to the character's resistance to the ailment's element.

With ailments using these resistances

A number of multipliers are applied to ailments after calculating the base rate, listed below

The final ailment rate is
If Ailment Rate would be more than 99%, it is instead 99%.

If an enemy lands a crit on an ally and does not inflict another mind ailment with that attack or if an ally attacks into a Null, Repel, or Drain, there's a chance that ally will be afflicted with Anxiety if they aren't already.

If playing on Regicide, add a flat 20% to the anxiety base rate.

Flags can be set by the game to either skip this process or guarantee the Anxiety attempt succeeds.

Ailment Recovery attempts occur only at the start of each turn. And it cannot happen the turn immediately after receiving the ailment.

Ailment Recovery rate is

Additionally, each ailment starts with some number of turns remaining that ticks down at the start of each turn. Once that ticks down to 0, a recovery is guaranteed.

Additionally, due to what appears to be an oversight, if any support effect (Tarukaja, Rebellion, Knight's Proclamation, etc.) on the afflicted expires at the start of their turn, all ailment recovery functions are skipped. This skips, among other things, decrementing the ailment timer, running the random recovery check, or even Instant Recovery's effect to recover from ailments immediately.

After acting, afflicted loses 5% of their max HP. Cannot be lethal.

Strength, Magic, Endurance, Agility, and Luck are reduced to 1/3rd their original value, before applying stat caps.
Healing does not affect the afflicted character.

Upon acting, 80% chance to be paralyzed and unable to move.
Note that, despite making the afflicted unable to move, it does not in any way hinder evasion.

Resistance damage multiplier for Dark is set to 3.0x against afflicted, regardless of the actual resistance level.
Ailment rates are doubled against afflicted when not using consumables.
After afflicted deals damage, afflicted takes damage equal to 50% of the total damage dealt to targets that survived the attack, rounded down.

After afflicted takes damage, afflicted takes additional damage equal to 30% of the total damage dealt, rounded down.

Afflicted's damage dealt is multiplied by 0.5x.

Overrides afflicted's action in ways that are not yet fully understood.

Afflicted's hit rate is multiplied by 0.5x.

Afflicted cannot use skills, but can still perform basic attacks, guard, pass, and use items.

Afflicted's action is lost, restoring an as of yet undocumented amount of HP and MP.
Afflicted cannot evade.
Attacks against afflicted that can crit will always crit.
Cured upon receiving non-Draining HP damage.

Afflicted is forced to perform a basic attack on their action.
Afflicted both deals and takes 2x damage.

Afflicted will perform archetype skills randomly when using them, the specifics of which are not known.
If an attack deals damage to afflicted, no press turn icon is removed.
Cured upon taking any HP damage from a character other than self.

Afflicted cannot act or evade.
20% chance to be cured upon taking HP damage from a source other than Opening Volley, Mortal Strike, or a source that Drains HP, once per attack (on the last hit).

If Fortune's Grasp and/or Archetypal Ring (does not stack) are found on the character, multiply A-EXP by 1.5.

Multipliers are applied to EXP and A-EXP based on the difference between the enemy's level and the player's level



Each enemy has a common drop and a rare drop, the odds of them giving their drop are

"Drop Rate" is the base drop rate for the item.

"Total Luck of Party" only includes the active party, not anyone in reserves.

"Lucky Find" is 20 if anyone in the party has the skill "Lucky Find" for common drops, or 20 if anyone in the party has the skill "Luckier Find" for rare drops. Otherwise this is 0.

"Regicide" is 2 if playing on the "Regicide" difficulty setting, otherwise it's 1.


Stealing can only steal the enemy's rare drop, and has one of the following Steal rates

Normal

Equipment with "Increases success of stealing skills."

"Plunder Bonus" is 20 if using Plunder instead of Steal.

"Drop Rate" is the base drop rate of the item being stolen. This can be any of 1, 2, 3, 4, 5, 8, 25, or 100 depending on the enemy being stolen from.

At 89 Agility or more, when using equipment to boost the success rate of stealing skills, it is impossible for Steal to fail provided there is an item to Steal.


The amount of MAG added to the battle result by Debt Collection is determined by

Since MAG gained this way is added to the battle result itself, it is affected by Unscathed Triumph, and is not gained if running away.


Pickpocket gives a 50% chance of receiving an enemy's common drop when stunning or killing them in the overworld while the protagonist is in Thief, Assassin, or Ninja. This chance cannot be modified.

♥♥♥♥♥'s Roguery's outcomes are split into the following table. Number of times ♥♥♥♥♥'s Roguery has been used is reset at the start of the player's turn


If

• The protagonist is attacked by an enemy
  
• The attack would strike the protagonist's weakness
  
• the attack used is single-target
  
• Hulkenberg is in the active party
  
• Hulkenberg has no ailments
  
• This ability has not been triggered previously this battle

then there is a chance the attack is redirected to Hulkenberg, depending on the ability unlocked

Hulkenberg is treated as guarding for a redirected attack.


If the ability "Victory Foresight" is unlocked, then the following behavior will occur.

At the start of each player's turn, the game checks Victory Foresight's turn counter.
If the turn counter is 0, then there is a 31% chance that Gallica adds 2 blinking Turn Icons.
If she adds turn icons, Victory Foresight's turn counter is set to a random value from 6 to 9.

At the end of each enemy turn, if Victory Foresight's turn counter is greater than 0, it is lowered by 1. This occurs before the above behavior.

Let me know if there's anything that I didn't cover here that you think should be. I'm still working on this, and would appreciate any suggestions for what to include or look into.

Spreadsheet with Skill, Equipment, and Enemy Data:
https://docs.google.com/spreadsheets/d/1FDC6T6tr__-AU18tY--4-ZUSzkeaMM_Kg_Crqu6VrcM/edit?usp=sharing

Spreadsheet with Character/Archetype stats and growths
https://docs.google.com/spreadsheets/d/1UF3G5-pp0uUm6c8i39B5-Zi6fATB2gaH-fHWpLgWxRs/edit?usp=sharing