Incorrect "Avoidance (Lvl +3)" value displayed

[jdelvare]

Bug description

The value displayed as "Avoidance (Lvl +3)" is off by 1.8 %. The computation misses the penalties for parry chance, block chance and dodge chance when the player is attacked by a creature of higher level.

Screenshots

Version

Anniversary Burning Crusade

I have prepared a fix already, I'll send a pull request.

[Alessandro-Barbieri]

Can you tell me more about the source of the formulas you are using?
Especially the part where you use only the base defense without talents.
I can't find any reference for classic nor for TBC

[jdelvare]

The fact that parry chances depend on the difference between the attacker's weapon skill and the player's defense skill is documented there.
The contribution from talents is listed separately, and the formula uses the "defense skill" and not the "defense value", which indicates that only the base defense value based on the player's level must be taken into account.

I have 2 reasons to believe that this is the right formula:

• If the defense bonus from talent Anticipation was included in the difference, then this talent's contribution to parry chances would actually be counted twice: once because every point of defense adds 0.04 % chance to parry, and a second time when computing the parry chance penalty based on the attacker's level.
• Using only the base defense skill without including the bonus defense from Anticipation, leads to the exact same total avoidance value as reported by Sixty Upgrades for my character. If I use the defense value including the +20 bonus from talent Anticipation, the total avoidance values no longer match.

Not sure what references I used for Block chance and Dodge chance, but the pages on the vanilla-wow-archive wiki give formulas similar to the Parry chance formula (that is, including a penalty based on the difference between the player's defense skill and the attacker's weapon skill). So my comment in GetParryChance() would also apply to GetBlockChance() and GetDodgeChance().

[Alessandro-Barbieri]

I read old wiki page comments and the magey wiki: everything points to this "Beaza formula" that appeared on the wiki (without any proof) years ago. In 2019 magey confirmed that the formula is right but

1. they used player vs mob data to confirm it (our case is mob vs player)
2. wording about what exactly "player defense" is still unclear

I don't know how to contact Beaza or Magey, maybe we can ask in the fight club discord but they are difficult to interact with.

[Alessandro-Barbieri]

I can try to see if the dataset used by magey can be useful to prove this thing

[Alessandro-Barbieri]

https://github.com/magey/tbc-warrior/wiki/Attack-table#dodge for reference

[Alessandro-Barbieri]

I tried to ask on the fight club discord but the shittalk was too much

[Alessandro-Barbieri]

Beanna from the fight club discord answered:

All these formulas always use the total of your character stats, never the base stats ignoring gear and talents. Otherwise it would be specified "base".

[jdelvare]

I don't know who Beanna is nor what kind of authority he represents on the matter. Maybe there was some misunderstanding in the discussion. What I know is that if we compute:

dodge = GetDodgeChance() + ((player's defense skill - enemy's attack skill) * some_factor)

where GetDodgeChance() is the API function provided by Blizzard which returns the same-level dodge chance percentage, then (player's defense skill - enemy's attack skill) must be zero when the player and the enemy are of same level with caped skills (attack skill = level * 5, defense skill = level * 5). Otherwise the returned value for a same-level mob simply can't match what is displayed by default in the game (which is the raw output of GetDodgeChance()). This obviously can only work if we use the player's base defense skill, because the enemy does not have anything else than their base attack skill to compare with.

I would add that the current ECS code returns the same Dodge, Parry and Block values as the DejaCharacterStats add-on for same-level attacking mob.

[Alessandro-Barbieri]

I think the addon should show, in two different categories, both the statistic that your character has (e.g. dodge % calculated with GetDodgeChance()) and the attack table result (e.g. dodge % calculated with GetDodgeChance() + (Data:GetDefenseValue() -enemyLevel * 5) * 0.04)
see also #357

[jdelvare]

I agree that displaying the attack table (for different mob/boss levels) would be a nice addition, but this is a feature request unrelated to this bug report.
And I persist in claiming that the formula above can't be correct. Any formula which does not result in a zero adjustment for a same-level attacker, can't be right, as it would return a value which differs from what the game itself is displaying.

[Alessandro-Barbieri]

Starting from the equation we have to implement 1 and the equation I suppose the game is using to display the dodge 2

1. Dodge = playerDodge + (playerDefense - enemyLevel * 5) * 0.04
2. GetDodgeChance() = playerDodge + (playerDefense - playerLevel * 5) * 0.04

Subtracting 2 from 1 gets:
Dodge = GetDodgeChance() + (playerLevel - enemyLevel) * 5 * 0.04

At the end the results are the same ...