This is a compilation of all kind of information regarding damage in Titan Quest AE. I will try to arrange it as coherent as possible.

All this knowledge has been tested over and over on version 2.9 of the Anniversary game (the latest version at the time I upload this document), tweaking weapons and monsters, resistances, health pools.

All damage mechanics are usually applied the same way in both ways: player damaging monster, and monster damaging player.

Please comment if you know any of this information is not accurate, I will gladly test it again.

With the option "All Damage" selected in the game preferences, really all the damage shown on screen is the damage done to the monster. The only "hidden" damage I know of is Percent health reduction, and the effect of damage absorption.

All instant damage is aggregated in one single damage number, color varies depending on damage majority, white is physical, pink is elemental, critical hits done by weapon damage will be always yellow, with different font size, regardless of the damage type.

Example: you do 50 physical + 200 fire, shows 250 pink. You do 60 physical as a critical of 1.2, plus the 200 fire, the value shown is 260 as yellow with the bigger font effect.

- All damage over time is aggregated in another single damage number, is always a pale orange color, the counter shown goes on if you reapply a DoT up to a few seconds after the displayed damage fades off.

- Poison and Bleeding duration bonus does not affect poison DPS. +100% duration on 100 poison over 3 secs is 200 poison over 6 secs as result.

- Damage over Time (DoT) damage does not stack from the dame source, it's re-applied: the duration is extended.

- Envenomed weapons augments (percent poison damage, extended duration) regardless of the tooltip, works on poison from any source.

- DoT application, the damage in application, and the duration is remembered individually, it doesn't strictly refresh previous applications, however, for any number of applications from the same source, only the highest damage will be in effect.

- In other words, If you re-apply poison from the same source with a different magnitude, the highest magnitude will be used against the monster until that application ends, each magnitude on application and its duration is tracked individually.

This is a bit complex so here's an example:

You attack with your poisoned weapon, a chance for extra poison damage triggers, applies 100 poison damage over 10 seconds, then after 5 seconds of damage (50 damage done), you attack again with the poisoned weapon, dealing only 10 poison damage over 10 seconds. From that point, will deal 50 poison damage during 5 seconds, then 5 poison damage during the next 5 seconds. This is useful with chance of total damage, debuff skills, burst damage from lethal strike...

- Weapon damage base cannot be augmented before damage calculations in any way. Bonus damage or physical damage on a weapon or a charm/relic in that weapon are considered separate sources of (non-weapon) damage. This is important because weapon damage has superior damage scaling from strength, and is the only source that can be converted and can crit (melee only) anything else is considered non-weapon damage.

- Bonus damage on weapon is special. Doesn't scale with percent physical damage, strength, or criticals, doesn't get converted to elemental with transmutation, doesn't get converted by weapon's pierce ratio, is always considered physical damage, so is mitigated by physical resistance and physical absorption, but ignores armor.

- Extra damage from weapon strength formula (IE 10 damage with 250 strength) doesn't scale with percent physical, is added to the weapon damage against armor.

- Every other source of physical damage will be considered as an independent source of non-weapon damage, scales with percent physical. IE: Physical damage from weapon affixes, rings, equipment, relics, artifacts, skills.

- On strength scaling: Weapon damage doubles at 500 strength and gets 20 extra damage. Non-weapon damage doubles at 650 strength. Each 100 strength means 15% extra non-weapon damage and 20% weapon damage plus 4 damage.

- Each source of physical damage will deal with armor independently. This means if you attack a monster with 100 armor with your weapon with a raptor tooth (physical damage charm) and a physical damage ring, using the Shield bash skill, the weapon damage, the damage from the charm, the damage from the ring, and the damage from the skill will deal with that 100 armor independently.

- Elemental conversion mainly from the rune skill, is applied before any calculation, having a 100 Phys damage base weapon with 50% conversion is exactly the same as a 50 Phys damage base weapon with a 50 elemental damage affix.

- Elemental damage is divided into the three flat elemental types, so: 60 elemental damage equals to 20 Fire + 20 Ice + 20 Lightning damage.

- Pierce damage from pierce ratio conversion on weapon is obtained from weapon physical damage after physical percent, strength, and crit are applied in the damage calculation, but before any mitigation from the target resistance/armor. Then the pierce percent and strength/dexterity formula for pierce ratio damage are applied.

- The pierce weapon damage formula is a complex one, strength lowers the multiplier, dexterity rises it, however, the extra pierce from strength from the previous calculation outweighs the loss in this formula. Even so, dexterity will give more pierce damage than strength applied in the two steps.

The exact formula is: (((pierceDamage % ((strength % 500) + 1)) x ((strength % 2000) + 1)) x ((dexterity % 400) + 1)) + (dexterity x 0.03)

If you do 50 weapon damage with 500 strength and +100% physical damage, the damage we are going to split for pierce ratio would be 220: (50 x 2 (percent phys) x 2 (str)) + 20 (str).

From this 220 physical damage, let's say we have a 50% pierce ratio: 110 damage will remain physical and will go against resistances and armor, the other 110 damage is base pierce damage.

If we have also +100% pierce, and 500 dexterity: (110 weapon pierce x 2 (percent pierce) x 1.55 (dex/str formula)) + 15 (dex/str formula) = 356 pierce damage. This damage goes against pierce resist/absorb.

Damage multipliers only affect one type of damage, and unlike damage resistances, are separated between instant damage and damage over time. So for Flat fire damage you need Percent Fire Damage, but for Burn Damage you need Percent Burn Damage. Damage multipliers of the same type are added together and applied before stat multipliers.

Percent Elemental Damage adds percent damage against all types of both flat and damage over time versions of Fire, Ice and Lightning damage.

Total Damage stack additively with other damage multipliers, both flat and over time, like Percent Fire, Percent Burn...

If you have 40% Fire Damage, 40% Elemental Damage and 40% Total Damage, has the same effect than 120% Fire Damage for flat fire damage.

Weirdly enough, Total Damage also augments the percent of Attack Damage Converted to health, and the duration of skill disruption.

So if you have 50% total damage, and you deal 20% Attack Damage Converted to health, and 2 seconds of skill disruption, is the same as 30% Attack Damage Converted to health and 3 seconds of skill disruption.

Remember you get 5% Total damage as hidden passive finishing the Hades Generals quest on Act 4, in each difficulty.

- Physical Resistance directly mitigates/augment all the incoming physical damage by a set percent: IE you do 200 physical damage (after all physical damage calculations, modifiers, strength, etc), the target has 20% physical resistance. Then your damage is 200 x (1 - 0.20) = 200 x 0.8 = 160 physical damage.

- Armor reduces a flat amount of physical damage, it's called "Armor Absorption", and is usually 66% of the armor value. Armor is not added altogether, instead, when attacking there's a chance a specific gear piece is targeted, 40% for chest, 20% for arms, boots and helmet. Beasts and other non-humanoid monsters doesn't have any gear equipped, but all enemy creatures have a passive armor that is always applied against physical damage.

From the example from before, we have 160 physical damage, the target also has 100 armor. 100 of our damage is 66% absorbed, the 60 remaining goes straight to the health pool.

So: (100 x (1 - 0.66)) + 60 = 34 + 60 = 94 final damage.

If the damage is lower than the armor all the damage is reduced by 66%. So if the target had 200 armor instead, vs the 160 damage.

(160 x (1 - 0.66)) = 54 final damage.

"-x% physical damage resistance", found on a few skills (Battle Standard - Triumph on warfare, Study prey on Hunting), is also applied before damage.

So if we do again 200 damage, and we place a battle standard with -50% physical damage resistance, the monster again has 20% physical resistance.

First, the monster resistance becomes -30% physical resistance due to the battle standard.

So: 200 x (1 - (-0.30)) = 200 x 1.3 = 260 damage. This value is reduced by Armor Absorption.

"x% reduced resistances" and "-x reduced resistances", are duration effects applied on hit (very similar to Poison, Bleeding), and doesn't count in the damage done with the hit that applies them.

As an example, Squall is a spell that hits every second during its duration (6 seconds). Obscured visibility adds a debuff that applies "x% reduced resistances" debuff over 6 seconds. So the first hit of squall won't benefit from the reduced resistances, but the effect will persist for 5 seconds more than squall duration if the monsters are hit with the last hit.

All types of resistances that are affected by this effect:

- All damage resistances (Physical, Bleeding, Cold, Vitality...).

- Armor protection values.

- Life Leach and Energy Leach resistances.

- Slow resistance (protect against Slow, Slow Attack and Slow Movement debuffs).

- Skill Disruption Resistance.

Deathchill aura -% Total Speed cannot be resisted/amplified as is not considered a debuff effect, is like a giving the enemies a buff that happens to be negative in value.

The same rule applies to affixes with these effects on weapons and gear/jewelry. On the first hit with the weapon (or a weapon skills, like dual-wield skills, shield skills, whirlwind, take down...), the debuff is applied, following hits will benefit of the reduced resistances while the debuff persists and is re-applied.

Example: Monster has 20% physical res and 200 armor.

We hit him with "-50 reduced resistances for 3 seconds": for 3 seconds, Monster has now -30% physical res and 150 armor.

We hit him with "50% reduced resistances for 3 seconds": for 3 seconds, Monster has now 10% physical res and 100 armor.

For details on the interaction between these reduction effects, of what i tested so far, everything explained in this post is true: https://titanquestfans.net/index.php?topic=238.0.

TL DR, all resistance reductions stack as long as comes from different sources, except X% reduced resistances, always uses only the greatest reduction value. -X% resistance only appear on some sort of debuff auras, usually from skills, the other two are debuff effects themselves.

Damage absorption has special mechanics behind:

- As with resistances, there's two variants: flat damage absorption and percent damage absorption. In some skills the absorption is applied to specific types of damage (some shield skills), but can be global (Rune: Sacred Rage, Dream: Trance of Convalescence)

- Damage absorbed is not shown on the damage done. The number on the screen is previous to damage absorption application.

- Damage absorption does not add together, each source is applied independently: if you have two sources of 40% absorption, means the damage is multiplied per 0.6 twice, and NOT 80% absorption.

- If you happen to have both flat and percent, first the percent is applied, then the flat is subtracted. If you have 50% percent and 50 flat, and you receive 180 damage, the final damage to health would be ((180 * 0.5) - 50) = 90 - 50 = 40.

- Damage absorbed is applied at the final step: reducing target health, does not interact with resistances or armor absorption.

This means if you do 100 physical damage after physical resistance and armor are applied, a 100 white number is shown on screen. However is the target is a ghost, the monster's health is only reduced by 40 points.

Absolute Damage Absorption does not affect Life Leech over time, but does affect Attack damage converted to health..

- For reference: Oozes (Slimes) have 70% piercing absorb. Ghosts have 60% pierce and physical absorb. Undead has 70% poison absorb. Constructs have 80% poison absorb.

There are five dual wield skills, you need any dual wield skill in order to be able to equip two weapons and use these skills: as how the skills are configured this happens as soon as you invest in either "Dual Wield" or "Reckless offense".

When dual wielding, every time you attack with either the basic attack or an attack replacer (Onslaught, Calculated Strike, Rune Weapon....), you will either attack with the left or right weapon, or a dual wield skill will trigger, with the damage from both weapons and a specific attack animation, but there's more into it:

Skills that work with both Melee and Thrown weapons:

Warfare - Dual Wield: 30% chance to happen at level 10/6. The player will attack once with each weapon in quick succession, with 10 extra physical damage in each weapon attack.

Rune - Reckless Offense: 27% chance to happen at level 16/12. With melee weapons attacks four times: swinging and dealing damage both weapons, twice. With throwing weapons are three attacks in quick succession, left, right, left always (is character's left hand, on equip screen is the one most at the right of the character window). Each weapon attack gets an extra 100% total damage modifier.

In a Berserker class (Warfare + Rune) you could have both skills for up to 57% chance of a dual wield skill to trigger with throwing weapons.

Skills that only work with melee weapons:

Warfare - Hew: 15% chance to happen at level 10/6. The player will make a jump and both weapons will hit at the same time, with an extra 50% physical damage modifier.

Warfare - Crosscut: 15% chance to happen at level 10/6. The player will attack with both weapons, dealing an attack with extra bleeding damage to up to two targets in 90 degrees front, damaging each target with both weapons.

Warfare - Tumult: 15% chance to happen at level 10/6. The player will make a 360 degree swinging animation, dealing an attack with extra bleeding damage and a 1 second stun to up three targets in melee distance at any direction, damaging each target with both weapons.

In a melee dual wield berserker, you could get theoretically up to 102% combined chance with all 5 skills at maximum level, and would always do a dual wield skill, but is NOT how it works.

There's also a minimum of a 20% chance of a normal attack.

When the all the dual wield skills and this 20% normal attack all combined are higher than 100%, the range is expanded, so at the end you have an absolute maximum of 20/122 (16.3%) of a normal attack, 30/122 (24.6%) of the Dual Wield skill, 27/122 (22.1%) of Reckless Offense, 15/122 (12.3%) and for each of Hew/Crosscut/Tumult skills.

Unarmed always is 100% attack speed base, affected directly by attack speed percent, multiplicatively.

The character has 75% base attack speed, weapons have a value that is added to this base speed.

Staves always add 10%, Bows 5% or 10%, Spears 10% or 15%, Maces/clubs 15%, 20% and 25%, Axes 30% or 35%, Sword 40%, 45% and 50%.

The tags Slow, Average, Fast, Very fast are assigned to weapons manually, there are some mistakes, but 95% of the time:
Very Slow 5% and 10%, Slow 15% and 20%, Average 25%, 30% and 35%, Fast 40% and 45%, Very fast 50%

One weapon, Two hands weapon, Weapon and shield: 15% reduction to base speed (character + weapon), multiplicatively.

Dual wield: Averages both weapons' speed. Adds extra 10% reduction to the one weapon attack speed, multiplicatively. ((character + weapon) x 0.85) x 0.9

Attack speed percent from weapons and items are added all together and affect the result also multiplicatively.

You have a 50% dagger and a 30% club and you dual wield. You also have +50% attack speed from equipment.

Your base is 75% + ((50% + 30%) % 2) = 75% + 40% = 115% base.

Then we apply the 15% reduction and the 10% extra reduction from dual wielding: (115% x (1 - 0.15)) x (1 - 0.10) = 115% x 0.85 x 0.9 = 88%

Then we apply the +50% attack speed: 88% x 1.50 = 132% This is the final speed shown on the character screen.

As a curiosity, if we divide 100 by our final attack speed shows up how frequently we launch an attack again. 100 % 132 = Every 0.76 seconds (normal speed).

There are different attack speed caps based on weapons:

- Unarmed: 350%.
- Staff: 229%.
- Single Melee weapon, Bow, or Melee weapon + shield: 222%.
- Single Thrown weapon or Thrown weapon + shield: 208%
- Dual wielding melee weapons: 200%
- Dual wielding Thrown weapons: 141%

The formula that determines the chance to hit range is:

(100 x (0.88 EXP ((100 + (DA - OA)) % 100))) + 10

If the range is inferior a 0.99, then the formula for reduced damage is applied, CTH_Range is the result of the above formula:

((CTH_Range % 2) + 45) / 100

Also, there's a chance equal to (100 - CTH_Range) to miss each attack you deal.

If the range is superior to 100, then for each attack there's a roll dice between 1 and the range result. If the rolled value is superior to 100, then a crit hit happens, with the following ranges:

10% extra damage: 100 - 104
20% extra damage: 104 - 110
30% extra damage: 110 - 117
40% extra damage: 117 - 124
50% extra damage: 125 +

The ranges are tailor-made to give access to a new crit range each 50 OA.

Some references (percents are rounded):

• If You need 9 more OA than target's DA in order to avoid damage reduction.
  
  
• If you have 100 more OA than target's DA, the range is 110, you have a 9% chance to make a critical hit, 3.6% chance to make 1.1x critical hit and a 5.4% chance to make a 1.2x critical hit.
  
  
• If you have 500 more OA than target's DA, the range is 176, you have a 43% chance to make a critical hit, and 30% chance to make 1.5x critical hit.
  
  
• If you have 200 less OA than target's DA, the range is 78, all hits will do 84% of original damage, or 16% reduced damage, and (100 - 78) 22% chance to miss the attack.
  
  
• If you have 500 less OA than target's DA, the range is 56, all hits will do 73% of original damage, or 27% reduced damage, and (100 - 56) 44% chance to miss the attack.

Just to wrap up, the damage reduction is applied before pierce ratio weapon conversion, just before/after resistance reduction, multiplicatively (order in this instance doesn't matter), only for physical melee damage.

Attack Damage converted to health (ADCtH) works with all types of instant/flat damage (fire, vitality, instant poison). Also works with Percent Health Damage.

Does not work with duration damage (Poison over time, Bleeding, Frostburn, Vitality Decay...)

While gets amplified by Total Damage, is not affected by Life Leech Percent. Gets reduced by damage absorption.

Resistances have a cap of 80%, but doesn't apply to monsters.

Lets list all type of resistances and their effect:

- Elemental (Fire, Ice, Lightning) resistances protect against both flat and damage over time versions of elemental damage (IE, both Lightning and Electric Burn). While flat elemental damage is divided equally into the three flat types, elemental resistance is added in full on all elemental types.

- Vitality protects against Flat Vitality, Vitality Decay and Percent health reduction.

- Poison Resistance protects against Instant poison and Poison over time.

- Bleeding resistance only protects against Bleeding over time (there's no flat version).

- Life leech resistance protects against Life leech over time and Attack Damage converted to health.

- Mana Leech resistance protect against mana leech over time, but also protects against mana burn.

- Sleep, Stun, Freeze, Trap, Petrification and Skill disruption resistances, all of them reduces the effect duration.

- Slow, Slow Attack speed and Slow Movement, are mitigated by Slow resistance, doesn't affect the duration but their magnitude.