Modifier

Modifiers are bonuses applied to items to increase their usefulness. They are determined by an item's affixes, each of which corresponds to a certain stat or attribute bonus. Some common modifiers include life, mana regeneration, weapon damage, attack/cast speed, movement speed, and attributes.

A magic item can have up to one prefix and one suffix, never two prefixes or two suffixes. Rare items can have up to three prefixes and three suffixes. Unique items do not have affixes, but are instead given specific modifiers. A randomly generated rare item (from a drop or Orb of Alchemy) receives between four and six affixes randomly, with a 1/12 chance of 6 affixes, 4/12 chance of 5 affixes, and 7/12 chance of 4 affixes.

All modifiers have a level associated with them, and will only appear on items with an item level greater than or equal to the modifier's level.

Modifier Stacking

In general, integer modifiers are applied before percentages. Percentage modifiers using the words "% increased" or "% reduced" stack additively with one another, while "% more" and "% less" modifiers stack multiplicatively. Multiplicative effects also affect each other, which results in a greater impact.

When dealing with weapons, some modifiers that are listed on the weapon itself are applied first, before mods from other pieces of equipment, skills, and so on. This includes anything affecting physical damage, such as increased physical damage, added physical damage, quality etc., and also attack speed, critical strike chance, critical strike multiplier, and accuracy. It does not include elemental damage mods.

Similarly, when dealing with armour, evasion, and energy shield on armour, any modifiers affecting those stats that are listed on the piece of armour are applied first. This includes quality and any other mods directly affecting armour, evasion, or energy shield amount. It does not include mods affecting the energy shield recharge delay or regeneration rate, only the amount of energy shield.

Quality behaves differently on armour and flasks than on weapons. On armour and flasks, it stacks multiplicatively with other modifiers on that piece of equipment.

Quality on weapons stacks additively with other % modifiers on the weapon.

Example

Imagine I have 100 life, and two passive skills that give "15% increased Maximum Life". These stack additively, so the result is

100 + (100 * .15) + (100 * .15), or

100 * (1 + .15 + .15) = 130 life

Now I equip an item that gives +40 life, and choose a passive skill that grants +20 life. The integer bonuses are applied first, so I end up with

(100 + 40 + 20) * (1 + .15 + .15) = 160 * 1.3 = 208 life

Now I choose two passive skills that gives "10% more Maximum Life". These are multiplicative, so they are applied separately.

(100 + 40 + 20) * (1 + .15 + .15) * 1.10 * 1.10 = 251.68 life

Note that if they were additive, the result would be

(100 + 40 + 20) * (1 + .15 + .15 + .1 + .1) = 240 life