Item drops and rarity

Game mechanics guide

Beta 0.7.2

Every item comes out of a chest, which rolls the item's rarity, level band, slot and base. After that nothing is random: two items with the same base, rarity and level have exactly the same affixes.

Where items come from

A kill gives gold, XP, progress toward a brown chest and a count toward pet hunts and the bestiary, but never an item: items, materials and gems all come out of chests.

Chest	From	Holds an item	Otherwise
Brown	Kills	50%	A material (40%, rarely a Dispel Scroll) or a gem (10%)
Blue	Stage bosses	90%	A gem (10%)
Red	Act bosses	90%	A gem (10%)

The very first brown chest of a new save always holds an item. From stage 6 on, brown and blue chests can turn into a riftstone instead; the chests page has the details and how often each chest comes. Items can also be forged or transmuted at the Workbench.

The rarity roll

Rarity is a weighted draw, and brown and blue chests cut the weights of Mythic and above. The forge rolls like a brown chest:

chance = weight ÷ sum of all weights

weight = base weight (the red-chest weight)

Mythic and up: × 0.42 in brown chests and the forge, × 0.55 in blue chests

Rarity	Base weight	Brown, no luck	Blue, no luck	Red, no luck
Common	1,000	68.28%	61.07%	52.73%
Uncommon	300	20.48%	22.55%	23.73%
Rare	120	8.19%	11.1%	14.24%
Heroic	42	2.87%	4.78%	7.48%
Mythic	5	0.143%	0.385%	1.33%
Legendary	1.2	0.0344%	0.114%	0.481%
Eternal	0.06	0.0017%	0.0028%	0.0061%

Chances are per item, with no Luck in the party. Blue and red chests also add Luck of their own, so every rarity above Common is more likely in them. The weights shipped with the client are much lower for the top rarities than the game's built-in defaults.

1 in 700Mythic, per brown-chest item

1 in 58,000Eternal, per brown-chest item

1 in 120,000Eternal, per brown chest

About, with no Luck. Only half of brown chests hold an item.

How luck changes it

Luck raises the weight of every rarity above Common, and more so the rarer it is. It has diminishing returns: the effective luck approaches 1 but never reaches it.

x = party Luck + chest bonus (brown 0, blue +30%, red +100%)

effective luck L = x ÷ (1 + x)

weight = base weight × (1 + L) ^ tier

tier = 0 for Common, 1 Uncommon, 2 Rare, 3 Heroic, 4 Mythic, 5 Legendary; Eternal uses 1.6

Eternal barely moves, because its weight grows with exponent 1.6 instead of 6. Drop find does not change rarity at all; it only changes how often chests come.

Party Luck	Common	Uncommon	Rare	Heroic	Mythic	Legendary	Eternal
0%	68.28%	20.48%	8.19%	2.87%	0.143%	0.0344%	0.0017%
5%	66.78%	20.99%	8.79%	3.22%	0.169%	0.0425%	0.0018%
10%	65.43%	21.41%	9.34%	3.57%	0.195%	0.0509%	0.0019%
25%	62.07%	22.35%	10.73%	4.5%	0.27%	0.0778%	0.0021%
50%	58.08%	23.23%	12.39%	5.78%	0.385%	0.123%	0.0023%
100%	53.3%	23.98%	14.39%	7.55%	0.567%	0.204%	0.0026%
Limit	40.55%	24.33%	19.47%	13.63%	1.36%	0.654%	0.0031%

"Limit" is where infinite Luck would take the brown chest and the forge: the odds stop improving well before any realistic Luck total.

Example: Luck 25% on a brown chest

Party Luck 25% on a brown chest: x = 0.25 and L = 0.2. The Heroic weight becomes 42 × 1.2³ = 72.6, while Common stays at 1,000. The Heroic chance rises from 2.87% to 4.5%.

Where Luck comes from

The Luck stat is stored in basis points (100 is 1%), and party Luck is the sum of every hero's Luck. Sources include:

Source	Luck
Codex	Rune of the Gambler +1% and Rune of Destiny +2%
Pets	Magpie +0.5%
Gear	Luck affixes (see affixes), the Topaz gem and the Fortune runeword (gems)
Class base stats	Healer +0.35%, Engineer +0.45%, Monk +0.5%, Witch +0.4%

Item level

Item levels come in bands: 1, 10, 20 and so on up to 100. An item takes the highest band at or below its raw level, and a hero can equip it from that level on.

Chest	Item level
Brown	As we read the code, the band of the stage's recommended level + 2: one or two levels before a band, already that band (see below).
Blue	As we read the code, the band of the stage's level + 2, but never above the level of the highest hero in the party. Near a band edge they reach the next band where a brown chest would not.
Red	The band of the act boss's level + 2: the Veil act 6 boss gives level-20 items, the Abyss act 10 boss level-100 items.

Why brown chests reach the next band early

The rule gives a chance of the next band two levels before it (33%) and one level before it (67%), tested against the same roll that dropped the chest. With the shipped settings no kill rolls a chest, so every brown chest comes from the kill guarantee, and for those the game tests a roll of 0, which is always under the chance. As we read the code, a brown chest one or two levels before a band therefore always gives that band.

Item levels in every act:

Map and act	Biome	Brown chest	Red chest
Veil 1	Isles	1	1
Veil 2	Swamp	1	1
Veil 3	Forest	1, 10	10
Veil 4	Desert	10	10
Veil 5	Canyon	10	10
Veil 6	Mountains	10, 20	20
Veil 7	Glaciers	20	20
Veil 8	Volcano	20	20
Veil 9	Floating Isles	20, 30	30
Veil 10	Deadlands	30	30
Breach 1	Isles	30	30
Breach 2	Swamp	30, 40	40
Breach 3	Forest	40	40
Breach 4	Desert	40	40
Breach 5	Canyon	40, 50	50
Breach 6	Mountains	50	50
Breach 7	Glaciers	50	50
Breach 8	Volcano	50, 60	60
Breach 9	Floating Isles	60	60
Breach 10	Deadlands	60	60
Abyss 1	Isles	60, 70	70
Abyss 2	Swamp	70	70
Abyss 3	Forest	70	70
Abyss 4	Desert	70, 80	80
Abyss 5	Canyon	80	80
Abyss 6	Mountains	80	80
Abyss 7	Glaciers	80, 90	90
Abyss 8	Volcano	90	90
Abyss 9	Floating Isles	90	90
Abyss 10	Deadlands	90, 100	100

Gems and materials follow the chest's level too. A gem's tier is 1 + the chest's level ÷ 20, rounded down, from 1 to 5. Materials are tier 1 at item level 1–10, tier 2 at 20–30, tier 3 at 40–50, tier 4 at 60–70 and tier 5 from 80.

Slot and base

Each slot a chest allows is equally likely. Jewelry only comes from boss chests (and the forge and transmuting):

Chest	Slots it can roll
Brown	Weapon, offhand, helmet, armor, legs, gloves, boots, belt: 1 in 8 each
Blue	10%: necklace, earrings, bracelet or ring, 1 in 4 each. 90%: the eight brown-chest slots.
Red	Any of the 12 slots, 1 in 12 each (jewelry 1 in 3)

Then the base is picked within the slot:

Slot	How the base is picked
Weapons and offhands	They belong to one class, and only that class can use them. The class is picked among the classes you own, in the party or on the bench. If you own classes that are not in the active party, 80% of rolls pick a party class, and all of them do with the game setting Loot only for the party on.
Armor	Heavy, medium or light, picked the same way among the weights your classes wear. A hero can only wear its own class's weight.
Jewelry	One of 6 bases for its slot, picked evenly.

Loot only for the party also covers the forge and transmuting (see Workbench). Every base and its affix list is on the items page.

Affixes and sockets

An item gets as many affixes as its rarity allows, always the first ones on its base's list, in order. The values are fixed by item level and rarity; nothing is rolled:

affix value = round down((base + per level × item level) × (1 + 0.5 × tier))

tier = 0 for Common up to 6 for Eternal, so ×1 to ×4

Rarity	Affixes	Affix multiplier	Gold value multiplier	Max sockets, weapon
Common	1	×1	×1	0
Uncommon	2	×1.5	×3	1
Rare	3	×2	×10	2
Heroic	4	×2.5	×30	3
Mythic	5	×3	×100	4
Legendary	6	×3.5	×300	5
Eternal	7	×4	×1,000	6

Weapons, offhands and jewelry list 6 affixes, so Legendary and Eternal both get all 6; armor lists 7, so only Eternal armor gets the 7th. The Workbench can add more on top: one extra affix from a scroll at the forge, an enchant, or on a weapon an infusion in place of the enchant.

Example: an Attack affix

A level-100 Eternal Attack affix is (4 + 2 × 100) × 4 = 816; the same affix on a level-1 Common item is (4 + 2) × 1 = 6.

Affix values by stat

Stat	Base	Per level	Level 1 Common	Level 100 Common	Level 100 Eternal
Attack	4	2	6	204	816
Haste	20	2	0.22%	2.2%	8.8%
Cast Speed	20	2	0.22%	2.2%	8.8%
Cooldown	20	2	0.22%	2.2%	8.8%
Crit Chance	25	3	0.28%	3.25%	13%
Crit Damage	50	5	0.55%	5.5%	22%
Chaos Damage	4	2	6	204	816
Elemental Damage	4	2	6	204	816
Health	20	8	28	820	3,280
Defense	3	2	5	203	812
Dodge	20	1	21	120	480
Accuracy	10	3	13	310	1,240
Block	20	1	21	120	480
Elemental Block	20	1	21	120	480
Absorption	2	1	3	102	408
Fire Resist	25	2	0.27%	2.25%	9%
Ice Resist	25	2	0.27%	2.25%	9%
Lightning Resist	25	2	0.27%	2.25%	9%
Chaos Resist	25	2	0.27%	2.25%	9%
Regen	1	1	2	101	404
Bleed	4	2	6	204	816
Decay	4	2	6	204	816
Fury	40	4	0.44%	4.4%	17.6%
Shock	40	4	0.44%	4.4%	17.6%
Curse	40	4	0.44%	4.4%	17.6%
Thorns	4	2	6	204	816
Poison	5	2	7	205	820
Weaken	40	4	0.44%	4.4%	17.6%
Blind	40	4	0.44%	4.4%	17.6%
Expose	40	4	0.44%	4.4%	17.6%
Penetration	40	4	0.44%	4.4%	17.6%
Elemental Penetration	40	4	0.44%	4.4%	17.6%
Move Speed	15	1	0.27%	1.92%	7.67%
Luck	15	2	0.17%	2.15%	8.6%

Base and per level are in the game's internal units: percentage stats in basis points (shown as % in the last three columns), the rest as raw stats. Health, Regen and Absorption are raw item values; on the hero sheet they count ×10, ×1.5 and ×5. Enhancing an item adds 5% to every affix per +1, up to +50% at +10.

Sockets

Every new item, whether dropped, forged or transmuted, comes with all its sockets already open and empty. How many depends on the slot and the rarity:

sockets = round(slot base × tier ÷ 6)

Slot (slot base)	Uncommon	Rare	Heroic	Mythic	Legendary	Eternal
Weapon, offhand, armor, legs (6)	1	2	3	4	5	6
Helmet, gloves, boots (4)	1	1	2	3	3	4
Belt, necklace (3)	1	1	2	2	3	3
Earrings, bracelet (2)	0	1	1	1	2	2
Ring (1)	0	0	1	1	1	1

Socketed gems give half their listed stats.

What we could not confirm

Read from the code, not yet checked in the live game:

Party Luck. Whether Luck from the Codex and pets counts once for the party or once per hero. This changes the real Luck totals.
Blue and red chests never give materials with the shipped settings.
Brown and blue chest levels. Both rules as described above, including brown chests reaching the next band early.
Identical affixes. Two drops with the same base, rarity and level should show identical affixes.
Health on item tooltips. Whether an item's Health shows raw or ×10 as on the hero sheet.
Server seeds. Sealed boss chests wait for a seed from the server, which may run the same roll itself. The launch build can also ship different weights.

Source: closed-beta game client 0.7.2. Data from the closed beta, so values may change at launch.