Legend: Legacy of the Dragons Forum

This guide gives some more information on attribtues described in the Library.

Sources for this guide are Administrators' answers on the Russian server forums.
Please note that many of those replies were given several years ago and I cannot guarantee nothing has changed since then.
The guide might be updated when I find some more interesting answers.

Strength
Increases physical damage. 10 units of Strength increase average physical damage by 1.

Damage
The damage you deal, usually given as a range from min damage to max damage.
The formulas for calculating damage are as follows:

min_damage = min_damage_attribute + Strength * 0.08
max_damage = max_damage_attribute + Strength * 0.12
damage = rand(0, max_damage - min_damage + 1)/2 + rand(0, max_damage - min_damage + 1)/2 + min_damage

Where min_damage_attribute and max_damage_attribute depend on your character's own damage attribute and the damage you get from items and blessings.
The random values in the damage formula are calculated twice to make sure that the extreme values (close to maximum or minimum) are less frequent.

Critical damage = 2.2 * normal damage

This is further affected by Talents:
your_crit_damage = damage * (220 + your_crit_increase - enemy_crit_protection)/100
(So the talents cancel each other out.)

Vitality
Increases the amount of life. Each unit of Vitality increases the maximum amount of life by 1.

Agility
Increases the chance to dodge enemy's physical attack. Reduces the enemy's chance of a critical strike.

Protection
Increases the chance to block enemy's non-critical physical attack. Reduces the enemy's chance of dodging. Slightly reduces non-critical damage.

Intuition
Increases the chance of dealing a critical blow. Reduces the enemy's chance of blocking a hit.

The higher the level of the opponent, the less effect each unit of Agility, Intuition and Protecton will have.

How do those stats translate into dodges/crits/blocks? Are there any formulas?
While no exact formulas have been shared by the administration, we know that the calculations for dodge, block, and crit take into account not only the value of the corresponding characteristic, but values of all combat stats in general (everything that affects the amount of life points and damage, so also vitality, strength, wisdom, protection, intuition, agility, etc.) of both opponents.

The higher the percentage of your agility in the sum of all your and your opponent's combat characteristics, the higher the chance of dodging the enemy's hit and the lower the chance of your enemy dealing a critical blow.

And in order to - for example - deal a critical blow, several checks must be passed:

• Your chance of crit must work (affected by your intuition),
  
• Your opponent cannot cancel your crit (chance of that happening depends on their agility),
  
• Opponent must not dodge (because dodge cancels crit) - that is checked for both their agility and your protection (since protection reduces the chance of enemy dodging).

Additionally, the chance of dodge/block/crit is limited by a certain maximum and minimum. Those values are decreased if you're wearing armour of different fighting styles - if you mix, for example, dodger and bonecrusher items, you will do fewer dodges/blocks/crits.

Protection, in addition to increasing the chance of blocking non-critical blow and decreasing the chance of opponent dodging, also decreases the incomiing non-critical damage by a certain percentage. The higher the share of your protection in the sum of all your and your opponent's combat characteristics, the higher the damage reduction will be.

Protection reducing non-critical damage, as well as agility/intuition/protection reducing the chance of opponent's crit/block/dodge only really work in battles where the participant's fighting style is determined (i.e. PvP), and is far less noticeable than the "main" effect - increased chance of dodge/crit/block.

Do monsters have a specific fighting style?
Monsters with pronounced style of combat are available on levels 3-10. All level 11+ bots have equal amount of agility, intuition, and protection.

Wisdom
Increases magic damage. 10 units of Wisdom increase the average magical damage by 1.

Intellect
Increases your mana. Each Intellect unit increases the maximum amount of mana by 1.

Suppression and Concentration
Suppression increases the chance of opponents (player) blundering the spells. Monsters never blunder.
The higher the level of the opponent, the less effect each unit of Suppression has.

Concentration reduces the chance of blundering your magical hits.
The higher the level of the opponent, the higher Concentration is required.
The base value of blundering against an opponent with the same or lower level is 4%.

The chance to blunder a spell is calculated based on the following formula:

chance_of_you_blundering = base_chance + 0.006 * (your_suppression / max(1, enemy_level - 10) - enemy_concentration / max(1, your_level - 10))

The base chance depends on the level difference between you and your opponent and is different for PvP and PvE fights. For example, in PvP, if both opponents have the same level, the base chance is 0.04. If there is a 1 level difference, the base chance is 0.06, if 2 levels - 0.09, and then it grows exponentially (but as far as I'm aware, the values have not been made public).

Penetration and Protection from magic
Protection from magic increases the chance to reflect part (25%, 50%, 75%, or 100%) of the enemy's magic attack.
The higher the level of the opponent, the less effect each Protection from Magic has.

Monsters usually have the same protection against all schools of magic, equal to 40 units for each level above 10, so for example a level 13 monster will likely have 120 protection against all kinds of magic. This rule doesn't apply to bosses, and creatures like elementals, mounts, summons.
With rare exceptions, monster spells do not have a school of magic, so protection from magic doesn't work against them.

Penetration reduces the chance of your magical attacks being reflected by the enemy. Each unit of Penetration reduces the Protection from Magic of the enemy by 1. Reducing protection below 0 does not have any effect on damage.

Average % of your damage being reflected is calculated by the following formula:
average_reflection = max(0, (enemy_protection - your_penetration)) / (4 * (your level - 10))
A calculator can be found here.

What average % means:
You can only reflect 0, 25, 50, 75, or 100% of damage. If you reflect 100% damage with probability 0.01, 75% with probability 0.04, 50% - 0.01, 25 - 0.15, and 0% with probability 0.7, the average reflected damage will be equal to:
0.01 * 1 + 0.04 * 0.75 + 0.1 * 0.5 + 0.15 * 0.25 = 0.1275
So on average damage will be reflected by 12.75%.
This is just an example, the exact probabilities have not been made public and are calculated using different formulas, separately for each protection effect.

Protection and penetration work only for specific schools of magic. If you're a Fire mage, you only need Fire-Air penetration, and you should only be concerned with your opponent's Fire-Air protection. Having penetration of other school has no effect at all, similarly protection from school of magic other than your opponent's will have no effect in combat.
If an item or effect does not specify the magic school, it means that it gives protection/penetration for all magic schools.

Will and Chance of magic crit
Will increases the chance to inflict a critical magic blow.
The higher the level of the opponent, the less the effect each Will has.

magic_crit_chance = magic_crit_chance_attribute + 0.5 * (your_will) / max(your_level - 10, enemy_level - 10, 1)

So for example if you're level 11 and your opponent is level 11 or lower, each unit of Will will give you +0.5% to the chance of magic crit.

Chance of magic crit lets you deal critical magic blows more often, regardless of the opponent's level. On levels 11+ all characters have a base 3% chance of magic crit. Items and blessings can increase it further. Additionally, Fire and Air spells have an additional 25-30% chance of magical crit.

Durability
Decreases physical and magical damage taken from other players. It has no effect on damage received from monsters, summons, mounts, etc. Durability is calculated according to the following formula:

final_damage = 1000 * damage_before_reduction / (1000 + your_durability / 1.2^your_level)

A calculator can be found here.

The damage reduction is multiplied with the reduction from other effects and protection from magic. For example, having -15% damage from durability, 50% reflected thanks to protection from magic, and -10% from other effects means that the final damage will be multiplied by a factor of 0.85 * 0.5 * 0.9 = 0.3825.

Durability also decreases the damage taken from - for example - shurikens.

Stun chance
Stun chance from various effects and items are all added up to one value which is checked at every hit. Super-blows that have a chance of stunning, such as Thirst for Blood, increase the total stun chance for one hit.

A character cannot be stunned two times in a row. If you were stunned, you cannot be stunned again until you have a turn (even if the enemy changes).

Effects expiring in battle
Any effects that increase attributes (strength, agility, durability, wisdom, etc.) by a specific number are "fixed" at the beginning of the fight and will not change until the end of the fight, even if the effects expire.
Effects that increase attributes by certain percent (including chance of crit, vampirism, etc.), as well as "ticking" effects (having an effect every X moves or seconds) will disappear as soon as their time is over.

Initiative
Increases your chance to have the first turn in a fight.

Most monsters have 0 initiative (and then having 100 initative gives you 100% chance of hitting first against them). Some have negative initiative (for example Spider, Emperor Scorpion, Fire Golem, Gurraldiy Korr) to avoid killing players immediatley after entering the battle. Some monsters (example - monsters from the Isles of Swirling Mist) have increased initative (50+). And some have very high initative (100+ - for example ling summons), since the first strike is important for their proper functioning.

If two players meet who have the same initiative, the chances are 50/50. A 20-point advantage would mean that the chance are approximately 58/42.

Prophecy
The probability of receiving Crystals of Truth and the maximum number of them that you can receive at once depend on the Prophecy skill. Prophecy from different effects/items adds up. With prophecy 7 or more, you have a chance to get 5 CoT at a time, with Porphecy 9 or more - 10 CoT at a time. If you have 10+ prophecy, there is a chance you will get 100 CoT at once.

Deterrence
This attribute has no impact on your combat skills or drop. However, it is useful in some quests, where having some Deterrence can open new ways of completing tasks.