Item Generation: iLvl, Mods, and Affixes

First of all I’d like to give a big thanks to d3inferno for scraping the MPQ files to gather the data required for this post. They provide a ton of information on the inner workings of Diablo 3 that is not available anywhere else.

Item Level

Item Level, or iLvl, is a property that determines the affixes an item can roll. It represents the statistical “budget” of it’s power. As you progress through the game, you fight monsters that have a level that is roughly equivalent to your characters level. When you kill them, they drop items with an iLvl less than or equal to their monster level or (mLvl).

Here is a full list of items and their corresponding iLvl.

When you get to Inferno, all monsters have a chance to drop items up to iLvl 63, which is the highest in the game right now. Consult the table below to get an idea what the drop rates are for different acts:

ILVL 61 9 % 18% 19% 24%
ILVL 62 2% 8% 12% 16%
ILVL 63 0% 2% 4% 8%

Please note that these rates are subject to change. Blizzard often releases patches that will alter the way items drop from different areas, this table may already be out of date.

Mods vs Affixes

These terms are NOT interchangeable. Consider the following item:

This item has 2 affixes and 2 mods. The prefix “Chromatic” has the mod of “Resistance to All Elements” associated with it. The suffix “of the Fortress” has the mod of “+x Armor” associated with it.

This item 2 affixes and 3 mods. The prefix “Potent” has 2 mods: “+x Dexterity” AND “+x Vitality”. The suffix “of the Fortress” has the mod of “+x Armor” associated with it.

This item also has 2 affixes and 3 mods. The prefix “Potent” has 2 mods: “+x Dexterity” AND “+x Vitality”. The suffix “of Pain” has the mod of “+x Dexterity.” Since both affixes add to dexterity, the mods stack.

Most affixes have only 1 mod associated with them, but a few, like “of Pain” have 2.

Affix Level

To keep low level items from rolling powerful affixes that would make the game too easy, the “affix level” (aLvl) is capped at the iLvl. Below is a table that shows the various affixes and their corresponding aLvl’s for the “Attack Speed” mod.

Affix Name Mod aLvl
Keen Attack Speed Increased by 2% 1
Keen Attack Speed Increased by 2% 8
Keen Attack Speed Increased by 2% – 3% 14
Raiding Attack Speed Increased by 2% – 3% 22
Raiding Attack Speed Increased by 3% – 4% 30
Raiding Attack Speed Increased by 3% – 4% 40
Assailing Attack Speed Increased by 5% 52
Assailing Attack Speed Increased by 6% – 7% 61
Assailing Attack Speed Increased by 8% – 9% 62
Vanquishing Attack Speed Increased by 10% – 11% 63

Magic and Rare Items

Magic (blue) items can have either 1 or 2 affixes: 1 prefix and 1 suffix. Rare (yellow) items can have between 4 and 6 affixes. These can be all prefixes or all suffixes, or a combination of both, but there are rules in place to keep certain affixes from spawning together.

Affix Groups

Rares can only roll affixes that are from different “groups.” For example, you can’t get “Vanquishing” and “Raiding” on the same item. Similarly, you can’t get “of Conflagration and “of the Heavens” for an absurd amount of elemental damage. For a full list of affixes and their corresponding groups, please refer to this link.

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