There are two modifiers that affect drop rates in the game, increased item rarity, and increased item quantity.
There are three potential sources of these modifiers:
- the player (skills, passives, gear etc.)
- monsters (such as bosses and champions)
- Party bonuses
Modifiers from the player stack additively with each other, and are subject to diminishing returns.
Modifiers from the party bonus and monsters stack additively with each other, and are not subject to diminishing returns.
The total player bonus stacks multiplicatively with the total party & monster bonus.
Increased Item Rarity
Increased Item Rarity % modifiers increase the chances of an item being magic, rare, or unique. For example with a total of +100% increased item rarity, you'd get twice as many magic items, twice as many rares and twice as many uniques from normal enemies.
This modifier has no effect on the number or type of currency items, scrolls, or gems that drop.
When in a party, only the modifier from the player who lands the killing blow on an enemy is counted.
If one of your minions gets a kill, the minion's IIR is added to yours and the total is used.
Magic, rare, and unique monsters have an Increased item rarity modifier for drops.
Increased Item Quantity
This modifier increases the average number of items that drop from monsters and chests. It does not affect the type, quality, or rarity of item dropped, only the chance that something will drop. There is no cap on the usefulness of this modifier, as monsters can drop more than one item at a time.
The base chance for an item to drop from a normal monster is 16%. This varies between monster types, and special monsters have higher drop chances.
When in a party, each player in the party after the first gives a +50% item quantity modifier on drops.
IIQ & IIR modifiers from support gems currently do not work with kills made by damage over time effects, such as the poison from poison arrow. Modifiers from your gear will affect those kills however.
Parties
The maximum party size is 6 players.
Effect on monsters
Monsters gain 50% extra life for each additional party member after the first. For example, against a party of 3 players, monsters have double life.
The original life amount is used for the purposes of determining the length of stuns and status ailments from elemental damage - this means monsters will not be harder to stun/ignite/etc. when fighting in a party.
Effect on loot
Each player in a party after the first gives a +50% item quantity modifier on drops. So a party of three will see twice as many drops as a lone character.
Increased Item Rarity & Quantity modifiers are only counted from the player who lands the killing blow.
See the drop rates section above for more information about item rarity and quantity bonuses.
Effect on experience
Only party members that are nearby (roughly two screens) receive experience from a slain monster. If one member is in town or too far from the monster they get no XP. Monsters are still made harder by players elsewhere on the level but outside of XP range.
Effect on flasks
Only the character landing the killing blow on an enemy will gain flask charges. The same is true for all +life and +mana gained "when you deal a killing blow" modifiers.
