Drop rates explained

[Brother Laz]

The quality of item drops is based on several factors: the stats in itemratio.txt, the treasure class (bosses drop better than regular monsters), and the item level compared to monster level.

The machine

The calculation used is:

Base chance: chance = itemratio - (mlvl-ilvl)/div
Multiplication for extra precision: chance = chance*128
EMF is counted in: chance = chance*100/(100+EMF)
Comparison to itemtypes Min: if (chance < minimum) then chance = minimum
The treasureclassex bonus is applied: chance = chance - (chance*tcbonus)/1024
Percentage chance to drop item: (128/chance)*100
If not, try again with the next lower item quality.

...where...

itemratio: unique, rare, set, magic, hiquality, normal in itemratio.txt.
div: UniqueDiv, RareDiv, SetDiv, MagicDiv, HiQualityDiv, NormalDiv in itemratio.txt.
EMF: Effective Magic Find, your MF after the diminishing returns are applied.
minimum: UniqueMin, RareMin, SetMin, MagicMin in itemratio.txt; 0 for superior and regular items.
tcbonus: Unique, Rare, Set, Magic in treasureclassex.txt associated with the treasure class.
ilvl: item level in weapons.txt or armor.txt; never exceeds 90.

EMF can be calculated from your MF stat:
Unique: if MF > 10 then EMF = MF*250/(MF+250) else EMF = MF
Set: if MF > 10 then EMF = MF*250/(MF+500) else EMF = MF
Rare: if MF > 10 then EMF = MF*250/(MF+600) else EMF = MF
Magic: EMF = MF

It first goes through these steps for unique items, then rares, then sets (yes, not the other way round), then magic items, then superior items, then normal items. If it fails all of the above, it is low quality.

Itemratio stats

Uniques
itemratio = 600
div = 4
minimum = 2200

If no unique is available for the current item at the current mlvl, drop a triple durability rare.

Rares
itemratio = 60
div = 5
minimum = 800

Sets
itemratio = 25
div = 5
minimum = 1500

If no set is available for the current item at the current mlvl, drop a double durability magic item.

Magic
itemratio = 10
div = 6
minimum = 128

Superior
itemratio = 4
div = 16
minimum = not applicable

Normal
itemratio = 3
div = 8
minimum = not applicable

Treasureclassex stats

Regular monsters: all 0
Champion/regular boss: magic = 1024, rest 0 (guaranteed magic drop)
Important boss: unique = 896; set = 896; rare = 960; magic = 1024 (*)
Important boss (quest): unique = 912; set = 912; rare = 976; magic = 1024 (**)

(*) Blood Raven, Andariel, Duriel, Mephisto, Izual, Hephaesto, Diablo, Nihlathak, Baal, Azmodan, Primus, High Cleric Dorian, High Cleric Gray, Inarius, Tal Rasha, Koth, Juris Khan, Inarius' Ghost, Ennead Necromancer, Malic, Lucion, Avatar of Zakarum.
(**) Andariel[quest], Duriel[quest], Mephisto[quest], Diablo[quest], Baal[quest].

So what do monsters drop, and how much of it?

The amount and selection of item dropped depends on the monster type. Bosses drop much more and different items than regular monsters.

The Countess

4 items are picked, each following this list:
25%: nothing
40%: gold
20%: item
10%: 'junk' (eg. arrows)
5%: ring, amulet, jewel, gem or rune

Additionally, she will try 3 times to drop a rune:
Hatred: 40% chance to drop Runes 5 (up to Thul); but capped at Ith due to mlvl, higher runes are discarded
Terror: 40% chance to drop Runes 10 (up to Lem)
Destruction: 40% chance to drop Runes 15 (up to Ber)
Quit after 3 tries or when reaching 6 items total.

The Summoner

4 items are picked, each following this list:
25%: nothing
25%: gold
25%: item
10%: 'junk'
15%: ring, amulet, jewel, gem or rune

Izual

4 items are picked, each following this list:
25%: nothing
45%: gold
25%: item
5%: 'junk'
10%: ring, amulet, jewel, gem or rune

Hephaesto

4 items are picked, each following this list:
25%: nothing
30%: gold
30%: item
10%: 'junk'
5%: ring, amulet, jewel, gem or rune

Andariel

5 (6 if quest drop) items are picked, each following this list:
20%: gold
45%: item (50% if quest drop)
10%: 'junk' (0% if quest drop)
5%: ring, amulet, jewel, gem or rune (10% if quest drop)
20%: rune, as follows:

Hatred: Runes 1 (El and Eld)
Terror: Runes 8 (up to Io)
Destruction: Runes 13 (up to Vex)

Other evils: Duriel, Mephisto, Diablo.

5 (6 if quest drop) items are picked, each following this list:
40%: gold
45%: item (50% if quest drop)
10%: 'junk' (0% if quest drop)
5%: ring, amulet, jewel, gem or rune (10% if quest drop)

Best bosses: Baal, Azmodan, Primus, High Cleric Dorian, High Cleric Gray, Inarius, Tal Rasha, Koth, Juris Khan, Inarius' Ghost, Ennead Necromancer, Malic, Lucion, Avatar of Zakarum.

4 (6 if Baal and quest drop) items are picked, each following this list:
15% (Hat/Ter) or 10% (Dest): gold
75%: item
5%: 'junk' (0% if quest drop)
5%: ring, amulet, jewel, gem or rune (10% if quest drop)
2.5% (Dest): guaranteed unique item

Superuniques: preset bosses that are the same in every game and are not among the above, eg. Fatal Morgana, Stormbane, Infernal Machine.

4 items are picked, each following this list:
2x 'Uitem' (~93.55% item, ~6.45% ring, amulet, jewel, gem or rune)
2x two potions

Uniques: random bosses, eg. Stone Maw the Tainted.

3 items are picked, each following this list:
1x 'Uitem' (~93.55% item, ~6.45% ring, amulet, jewel, gem or rune)
2x two potions

Normal melee monsters: regular monsters with a melee attack.

1 item is picked, following this list:
61.73%: nothing
12.96%: gold
12.96%: 'junk'
9.88%: item
2.47%: ring, amulet, jewel, gem or rune

Normal caster monsters: regular monsters with a spell attack.

1 item is picked, following this list:
59.17%: nothing
12.43%: gold
12.43%: 'junk'
9.47%: item
2.37%: ring, amulet, jewel, gem or rune
4.14%: potion or scroll

Normal missile monsters: regular ranged physical monsters.

1 item is picked, following this list:
58.48%: nothing
12.28%: gold
12.28%: 'junk'
9.36%: item
2.33%: ring, amulet, jewel, gem or rune
3.51%: guaranteed bow
1.75%: ammo

The bottom line is that it does pay off to hunt monsters with a missile attack if you are looking for bows. Unfortunately, the only missile monsters are quill rats, javelin cats, rogue archers, blowdart fetish, skeleton archers and acid dogs (bug).

Regular chests and containers

Object TCs are grievously hardcoded to the level ID, meaning an uberlevel in Act 1 will drop an Act 1 TC no matter what. I think it will use a higher level auto-TC if the area level is higher, though.

Either way, on Destruction difficulty, all monsters (and objects) can drop all base items anyway; and there are no differences in drop chance between Act 1 and Act 5 TCs in Destruction, except when it comes to 'junk'.

Anyway. Not all chests and containers will even get to the drop part:

Chests: If the chest is not locked, 25% chance to proceed to the next step. If the chest is locked, always proceed to the next step.

Objects: If the object is an urn, rock pile, basket, jar or barrel, 21% chance to proceed to the next step. If the object is anything else, always proceed to the next step.

6 items are picked, each following this list:
25.00%: nothing
41.67%: gold
12.50%: 'junk'
16.67%: item [! much higher than regular monsters]
4.17%: ring, amulet, jewel, gem or rune

Objects that are not chests will go through the drop routine once, then quit.

Locked chests go through the drop routine twice, regular chests once. If none of the items is at least magic quality, do another chest drop, up to 10 times or until a magic item is dropped. (This is responsible for the 'garbage fountain' effect)

Special chests

A very rare type of chest. Special chests look normal, but have improved drops. They spawn at the dead ends in the Arcane Sanctuary among other places.

Special chests drop like regular chests, but have 95% chance to drop magic items only, 5% chance to drop rare items only.

Sparkly chests

Our precious. We all know the 'unique fountain' phenomenon, and here is why it occurs. Sparkly chests can do 6 different things depending on a random roll:

1. (2%): Do a regular chest drop, and try to make every item unique (unique fountain!). If none of the items are magic or better, do another chest drop and try to make every item unique. If none of the items are magic or better again, go to 6.
2. (4%): Do a regular chest drop, and try to make every item set. If none of the items are magic or better, do another chest drop and try to make every item set. If none of the items are magic or better again, go to 6.
3. (6%): Do a regular chest drop, and try to make every item rare. If none of the items are magic or better, do another chest drop and try to make every item rare. If none of the items are magic or better again, go to 6.
4. (20%): Do a regular chest drop, and try to make every item magic. Repeat until at least 3 items are magic or up to 10 times.
5. (30%): Do a regular chest drop, and try to make every item magic. Repeat until at least 2 items are magic or up to 10 times.
6. (38%): Do a regular chest drop, and try to make every item magic. Repeat until at least 1 item is magic or up to 10 times. Then it will drop up to 4 random items from the 'chest' drop with a random quality (ie. MF matters).

Racks

Racks will go through all suitable weapons or armors (only metal weapons) and pick one, bypassing the regular treasure classes. There is a special rarity setting in weapons.txt and armor.txt that controls how often they will spawn on racks, but generally speaking you are much more likely to find a high level item off a rack than from a monster. Rack running can be worth it if you are looking for tier 6 or sacred items.

*** So how are item drops within those TC subgroups calculated?

'Item': This drops an item from the auto-TC groups. It will randomly choose armor or weapon, then roll for a base item. This is complicated, because it uses a cascade system - each TC line has a chance to cascade down to the next lower TC instead of drop an item. For this reason, I cannot give a simple formula. (*)

Either way, this factor is not modified by anything else, not MF, not monster level. The higher your 'item' drop chance, the more items you will find. That's all you need to know.

(*) See below in the 'Auto TCs' section, though.

'Ring, amulet, jewel, gem or rune': This one depends on the place where the drop occurs; in Act 5 Destruction and any of the uberquests, the distribution looks like this:

32.26%: jewelry (57.14% ring, 28.57% amulet, 14.29% jewel)
5.38%: chipped gem
7.53%: flawed gem
9.68%: normal gem
11.83%: flawless gem
13.98%: perfect gem
19.35%: rune

'Potion or scroll': Also depends on the place where the drop occurs; from late Act 5 Hatred onwards, the distribution looks like this:

16.67%: town portal scroll
33.33%: identify scroll
16.67%: greater mana potion
33.33%: super mana potion

'Junk': This is hard to explain, because it uses a cascade system similar to item treasure groups. This is a particularly egregious bit of spaghetti TCs. It doesn't matter, because all it drops is potions, scrolls, ammo and elixirs.

Auto TCs

When the game decides to drop an 'item', it picks one depending on monster level. For this purpose, items are grouped in 'auto TCs', which collect all items of the corresponding type with an ilvl of (TC level -2 to TC level). You can find an ilvl table on the Median 2008 homepage.

Min level 0 -- weap3: 50%; armo3: 50%
Min level 5 -- weap3: 15%; armo3: 15%; weap6: 35%; armo6: 35%
Min level 9 -- weap3: 5.55%; armo3: 2.77%; weap6: 16.66%; armo6: 8.33%; weap9: 38.88%; armo9: 19.44%; weap12: 5.55%; armo12: 2.77%
Min level 12 -- weap6: 4.87%; armo6: 2.43%; weap9: 14.63%; armo9: 7.31%; weap12: 34.14%; armo12: 17.07%; weap15: 4.87%; armo15: 2.43%; next lower treasure class: 12.19%
Min level 15 -- weap9: 4.44%; armo9: 2.22%; weap12: 13.33%; armo12: 6.66%; weap15: 31.11%; armo15: 15.55%; weap18: 4.44%; armo18: 2.22%; next lower treasure class: 20%
Min level 18 -- weap12: 4.16%; armo12: 2.08%; weap15: 12.5%; armo15: 6.25%; weap18: 29.16%; armo18: 14.58%; weap21: 4.16%; armo21: 2.08%; next lower treasure class: 25%
Min level 20 -- weap15: 3.92%; armo15: 1.96%; weap18: 11.76%; armo18: 5.88%; weap21: 27.45%; armo21: 13.72%; weap24: 3.92%; armo24: 1.96%; next lower treasure class: 29.41%
Min level 22 -- weap18: 3.63%; armo18: 1.81%; weap21: 10.9%; armo21: 5.45%; weap24: 25.45%; armo24: 12.72%; weap27: 3.63%; armo27: 1.81%; next lower treasure class: 34.54%
Min level 24 -- weap21: 3.44%; armo21: 1.72%; weap24: 10.34%; armo24: 5.17%; weap27: 24.13%; armo27: 12.06%; weap30: 3.44%; armo30: 1.72%; next lower treasure class: 37.93%
Min level 26 -- weap24: 3.17%; armo24: 1.58%; weap27: 9.52%; armo27: 4.76%; weap30: 22.22%; armo30: 11.11%; weap33: 3.17%; armo33: 1.58%; next lower treasure class: 42.85%
Min level 29 -- weap27: 2.98%; armo27: 1.49%; weap30: 8.95%; armo30: 4.47%; weap33: 20.89%; armo33: 10.44%; weap36: 2.98%; armo36: 1.49%; next lower treasure class: 46.26%
Min level 32 -- weap27: 2.73%; armo27: 1.36%; weap30: 8.21%; armo30: 4.1%; weap33: 19.17%; armo33: 9.58%; weap36: 2.73%; armo36: 1.36%; next lower treasure class: 50.68%
Min level 34 -- weap30: 2.59%; armo30: 1.29%; weap33: 7.79%; armo33: 2.59%; weap36: 18.18%; armo36: 9.09%; weap39: 2.59%; armo39: 1.29%; next lower treasure class: 54.54%
Min level 36 -- weap30: 2.4%; armo30: 1.2%; weap33: 7.22%; armo33: 2.4%; weap36: 16.86%; armo36: 8.43%; weap39: 2.4%; armo39: 1.2%; next lower treasure class: 57.83%
Min level 38 -- weap33: 2.19%; armo33: 1.09%; weap36: 6.59%; armo36: 3.29%; weap39: 15.38%; armo39: 7.69%; weap42: 2.19%; armo42: 1.09%; next lower treasure class: 60.43%
Min level 40 -- weap33: 2.02%; armo33: 1.01%; weap36: 6.06%; armo36: 3.03%; weap39: 14.14%; armo39: 7.07%; weap42: 2.02%; armo42: 1.01%; next lower treasure class: 63.63%
Min level 42 -- weap36: 1.86%; armo36: 0.93%; weap39: 5.6%; armo39: 2.8%; weap42: 13.08%; armo42: 6.54%; weap45: 1.86%; armo45: 0.93%; next lower treasure class: 66.35%
Min level 44 -- weap36: 1.72%; armo36: 0.86%; weap39: 5.17%; armo39: 2.58%; weap42: 12.06%; armo42: 6.03%; weap45: 1.72%; armo45: 0.86%; next lower treasure class: 68.96%
Min level 46 -- weap39: 1.58%; armo39: 0.79%; weap42: 4.76%; armo42: 2.38%; weap45: 11.11%; armo45: 5.55%; weap48: 1.58%; armo48: 0.79%; next lower treasure class: 71.42%
Min level 48 -- weap39: 1.45%; armo39: 0.72%; weap42: 4.37%; armo42: 2.18%; weap45: 10.21%; armo45: 5.1%; weap48: 1.45%; armo48: 0.72%; next lower treasure class: 73.72%
Min level 50 -- weap42: 1.34%; armo42: 0.67%; weap45: 4.02%; armo45: 2.01%; weap48: 9.39%; armo48: 4.69%; weap51: 1.34%; armo51: 0.67%; next lower treasure class: 75.83%
Min level 52 -- weap42: 1.22%; armo42: 0.61%; weap45: 3.68%; armo45: 1.84%; weap48: 8.58%; armo48: 4.29%; weap51: 1.22%; armo51: 0.61%; next lower treasure class: 77.91%
Min level 54 -- weap45: 1.12%; armo45: 0.56%; weap48: 3.38%; armo48: 1.69%; weap51: 7.9%; armo51: 3.95%; weap54: 1.12%; armo54: 0.56%; next lower treasure class: 79.66%
Min level 56 -- weap45: 1.03%; armo45: 0.51%; weap48: 3.1%; armo48: 1.55%; weap51: 7.25%; armo51: 3.62%; weap54: 1.03%; armo54: 0.51%; next lower treasure class: 81.34%
Min level 58 -- weap48: 0.94%; armo48: 0.47%; weap51: 2.84%; armo51: 1.42%; weap54: 6.63%; armo54: 3.31%; weap57: 0.94%; armo57: 0.47%; next lower treasure class: 82.93%
Min level 60 -- weap48: 0.86%; armo48: 0.43%; weap51: 2.59%; armo51: 1.29%; weap54: 6.06%; armo54: 3.03%; weap57: 0.86%; armo57: 0.43%; next lower treasure class: 84.41%
Min level 62 -- weap51: 0.79%; armo51: 0.39%; weap54: 2.38%; armo54: 1.19%; weap57: 5.55%; armo57: 2.77%; weap60: 0.79%; armo60: 0.39%; next lower treasure class: 85.71%
Min level 64 -- weap51: 0.72%; armo51: 0.36%; weap54: 2.17%; armo54: 1.08%; weap57: 5.07%; armo57: 2.53%; weap60: 0.72%; armo60: 0.36%; next lower treasure class: 86.95%
Min level 66 -- weap54: 0.66%; armo54: 0.33%; weap57: 1.98%; armo57: 0.99%; weap60: 4.63%; armo60: 2.31%; weap63: 0.66%; armo63: 0.33%; next lower treasure class: 88.07%
Min level 68 -- weap54: 0.6%; armo54: 0.3%; weap57: 1.81%; armo57: 0.9%; weap60: 4.24%; armo60: 2.12%; weap63: 0.6%; armo63: 0.3%; next lower treasure class: 89.09%
Min level 70 -- weap57: 0.55%; armo57: 0.27%; weap60: 1.65%; armo60: 0.82%; weap63: 3.86%; armo63: 1.93%; weap66: 0.55%; armo66: 0.27%; next lower treasure class: 90.05%
Min level 71 -- weap57: 0.5%; armo57: 0.25%; weap60: 1.51%; armo60: 0.75%; weap63: 3.53%; armo63: 1.76%; weap66: 0.5%; armo66: 0.25%; next lower treasure class: 90.9%
Min level 73 -- weap60: 0.46%; armo60: 0.23%; weap63: 1.38%; armo63: 0.69%; weap66: 3.22%; armo66: 1.61%; weap69: 0.46%; armo69: 0.23%; next lower treasure class: 91.7%
Min level 75 -- weap60: 0.42%; armo60: 0.21%; weap63: 1.26%; armo63: 0.63%; weap66: 2.94%; armo66: 1.47%; weap69: 0.42%; armo69: 0.21%; next lower treasure class: 92.43%
Min level 76 -- weap63: 0.38%; armo63: 0.19%; weap66: 1.14%; armo66: 0.57%; weap69: 2.68%; armo69: 1.34%; weap72: 0.38%; armo72: 0.19%; next lower treasure class: 93.1%
Min level 77 -- weap63: 0.34%; armo63: 0.17%; weap66: 1.04%; armo66: 0.52%; weap69: 2.44%; armo69: 1.22%; weap72: 0.34%; armo72: 0.17%; next lower treasure class: 93.71%
Min level 78 -- weap66: 0.31%; armo66: 0.15%; weap69: 0.95%; armo69: 0.47%; weap72: 2.22%; armo72: 1.11%; weap75: 0.31%; armo75: 0.15%; next lower treasure class: 94.26%
Min level 79 -- weap66: 0.28%; armo66: 0.14%; weap69: 0.86%; armo69: 0.43%; weap72: 2.02%; armo72: 1.01%; weap75: 0.28%; armo75: 0.14%; next lower treasure class: 94.78%
Min level 80 -- weap69: 0.26%; armo69: 0.13%; weap72: 0.79%; armo72: 0.39%; weap75: 1.84%; armo75: 0.92%; weap78: 0.26%; armo78: 0.13%; next lower treasure class: 95.24%
Min level 81 -- weap69: 0.24%; armo69: 0.12%; weap72: 0.72%; armo72: 0.36%; weap75: 1.68%; armo75: 0.84%; weap78: 0.24%; armo78: 0.12%; next lower treasure class: 95.66%
Min level 82 -- weap72: 0.21%; armo72: 0.1%; weap75: 0.65%; armo75: 0.32%; weap78: 1.53%; armo78: 0.76%; weap81: 0.21%; armo81: 0.1%; next lower treasure class: 96.05%
Min level 83 -- weap75: 0.19%; armo75: 0.09%; weap78: 0.59%; armo78: 0.29%; weap81: 1.39%; armo81: 0.69%; weap84: 0.19%; armo84: 0.09%; next lower treasure class: 96.4%
Min level 84 -- weap78: 0.18%; armo78: 0.09%; weap81: 0.54%; armo81: 0.27%; weap84: 1.27%; armo84: 0.63%; weap87: 0.18%; armo87: 0.09%; next lower treasure class: 96.73%
Min level 85 -- weap81: 0.16%; armo81: 0.08%; weap84: 0.49%; armo84: 0.24%; weap87: 1.15%; armo87: 0.57%; weap90: 0.16%; armo90: 0.08%; next lower treasure class: 97.02%

When an auto TC is chosen (for example, armo78), it will roll for an item within this auto TC. This includes the following items:

Full Plate Mail (Grade 5)
Crown (Grade 5)
Gothic Shield (Grade 5)
Spirit Mask (Grade 5)
Avenger Guard (Grade 5)
Crown Shield (Grade 5)
Demon Head (Grade 5)
Diadem (Grade 5)
Gambeson (Grade 6)
Gambeson (Sacred)
Small Shield (Grade 6)
Light Belt (Grade 6)
Heavy Gloves (Grade 6)
Heavy Boots (Grade 6)
Targe (Grade 6)
Preserved Head (Grade 6)
Small Shield (Sacred)
Light Belt (Sacred)
Heavy Gloves (Sacred)
Heavy Boots (Sacred)
Targe (Sacred)
Preserved Head (Sacred)
Banded Plate (Grade 5)
Spangenhelm (Grade 5)
Ancient Armor (Grade 5)
Studded Leather (Grade 6)
Skull Cap (Grade 6)
Wolf Head (Grade 6)
Jawbone Cap (Grade 6)
Studded Leather (Sacred)
Skull Cap (Sacred)
Wolf Head (Sacred)

Not every item is equally likely to be chosen. Regular items have a chance of 3. Assassin claws have a chance of 2. All other class-specific items have a chance of 1. Sacred items were intended to have a chance of 1 as well, but this is not applied due to a bug.

/players X and nodrops

Higher /players settings affect the chance to drop 'nothing'. The game does this by applying an exponent to the nodrop chance, based on number of players:

1 for self and each partied and nearby player.
0.5 for each unpartied or distant player. (Stick together, team!)

For example, if a TC has 20% chance to drop nothing, in a 2 player game, it will have only 4% chance to drop nothing. In a 4 player game, it will have only 0.2^4 = 0.0016 or 0.16% chance to drop nothing.

As you see, the nodrop chance goes down very quickly. Before long, nodrop will be rounded down to 0%.

Example

1. Let's kill a level 121 Ethereal in a /players 4 game, looking for The Black Dame, the sacred unique long war bow (base item ilvl=90).

It drops like a regular melee monster, meaning it has 0,61728395... (61.73%) chance to drop 'nothing'. But since this is /players 4, it has only 0,61728395...^4 = 0,145191082... = 14.52% chance to drop nothing.

Of course, the different drops now add up to 52.79% chance instead of 100.00%. The other drop options have not changed relative to each other, they are just more likely to happen because 'nothing' is lower.

So we have to rescale the other chances by multiplying them with (100-14.52 [new nodrop %])/(100-61.73 [old nodrop %]) = 2,24.

14.52%: nothing
28.95%: gold
28.95%: 'junk'
22.07%: item
5.52%: ring, amulet, jewel, gem or rune

In other words, 22.07% of our /players 4 Ethereal will drop an item, using the highest treasure class, the one with a level of 85 or up.

This treasure class has a 0.16% chance to drop a weap90 item, according to that huge list a few paragraphs up.

The weap90 auto-TC comprises:

3- War Sword (Grade 6)
3- Great Sword (Grade 6)
3- Crystal Sword (Grade 6)
3- Long War Bow (Grade 6)
3- Repeating Crossbow (Grade 6)
1- Hand of God (Grade 6)
1- Reflex Bow (Grade 6)
2- Blade Talons (Grade 6)
2- Scissors Katar (Grade 6)
1- Recurve Bow (Grade 6)
1- Kriegsmesser (Grade 6)
1- Trebuchet (Grade 6)
3- War Sword (Sacred)
3- Great Sword (Sacred)
3- Crystal Sword (Sacred)
3- Long War Bow (Sacred)
3- Repeating Crossbow (Sacred)
1- Hand of God (Sacred)
1- Reflex Bow (Sacred)
2- Blade Talons (Sacred)
2- Scissors Katar (Sacred)
1- Recurve Bow (Sacred)
1- Kriegsmesser (Sacred)
1- Trebuchet (Sacred)

Our bow has 3/48 chance to be picked, ie. 6.25%.

Multiplying the above percentages, our Ethereal has a 0.002207% chance to drop a Sacred Long War Bow (ack!). If through some miracle it does drop one:

You have 300% MF:

Unique: EMF = 136%

Base chance: chance = 600 - (121-90)/4 = 592.25 (= 0.17% chance w/o MF)
Multiplication for extra precision: chance = chance*128 = 75808
EMF is counted in: chance = chance*100/(100+136) = 32122
Comparison to itemtypes Min: if (chance < 2200) then chance = minimum
The treasureclassex bonus is 0 for regular monsters.
Percentage chance to drop item: (128/chance)*100 = 0.39848079...%
Chance to drop unique item: 0.40%.

The remaining 99.60% will then roll for rare, set, magic, high quality and normal in the same fashion.

In the end, you have a 0.000008828% (1 in 11360780) chance that a given Ethereal will drop you a Black Dame. As you see, this is not the best MF option...

2. Let's kill a level 121 Avatar of Zakarum. It drops 4 items, each of which has 75% chance to be an 'item'. To find out what your chance is to get an 'item', you're going to need some probability math. I'm not good at probabilities. I hope this is correct:

0 'item' drops: 3.91%
1 'item' drop: 4.69%
2 'item' drops: 21.09%
3 'item' drops: 42.19%
4 'item' drops: 31.64%

It will drop 3 items on average. Each of these items again has 0.16% chance to pick from weap90, and then 6.25% chance to choose a sacred long war bow. You have 300% MF:

Base chance: chance = 600 - (121-90)/4 = 592.25 (= 0.17% chance w/o MF)
Multiplication for extra precision: chance = chance*128 = 75808
EMF is counted in: chance = chance*100/(100+136) = 32122
Comparison to itemtypes Min: if (chance < 2200) then chance = minimum
The treasureclassex bonus is applied: chance = 32122 - (32122*896)/1024 = 4016
Percentage chance to drop item: (128/chance)*100
Chance to drop unique item: 3.19%.

Hmm, that looks better. You now have a 0.000957% (1 in 104493) chance that a given Avatar of Zakarum will drop a Black Dame.

3. A more realistic example: you kill a (level 82) monster in an attempt to find a rare War Sword (5). This item has an ilvl of 77. The treasure class with a level of 82 has 1.53% chance to drop weap78. There are 38 items in this auto-TC:

3- Crystal Sword (Grade 5)
3- Long War Bow (Grade 5)
3- Scimitar (Grade 6)
3- Repeating Crossbow (Grade 5)
1- Reflex Bow (Grade 5)
2- Wrist Blade (Grade 6)
3- Scimitar (Sacred)
2- Wrist Blade (Sacred)
1- Hand of God (Grade 5)
3- War Sword (Grade 5)
3- Great Sword (Grade 5)
3- Pilum (Grade 6)
3- Trident (Grade 6)
3- Long Staff (Grade 6)
2- Blade Talons (Grade 5)
2- Scissors Katar (Grade 5)
1- Sacred Globe (Grade 6)
3- Pilum (Sacred)
3- Trident (Sacred)
3- Long Staff (Sacred)
1- Sacred Globe (Sacred)
1- Recurve Bow (Grade 5)
1- Trebuchet (Grade 5)
3- Claymore (Grade 6)
3- Axe (Grade 6)
3- Broad Axe (Grade 6)
3- Spiked Club (Grade 6)
3- Long Bow (Grade 6)
3- Yew Wand (Grade 6)
3- Light Crossbow (Grade 6)
3- Claymore (Sacred)
3- Axe (Sacred)
3- Broad Axe (Sacred)
3- Spiked Club (Sacred)
3- Long Bow (Sacred)
3- Yew Wand (Sacred)
3- Light Crossbow (Sacred)
1- Kriegsmesser (Grade 5)

Our sword has a 3/93 = 3.23% chance to be picked.

In the end, any (level 82) monster has 0.050% chance to drop a tier 5 war sword. If you have 100% MF (71 EMF for uniques, 35 EMF for rares):

Base chance: chance = 600 - (82-77)/4 = 598 (= 0.17% chance w/o MF)
Multiplication for extra precision: chance = chance*128 = 76544
EMF is counted in: chance = chance*100/(100+71) = 44762
Comparison to itemtypes Min: if (chance < 2200) then chance = minimum
The treasureclassex bonus is 0 for regular monsters.
Percentage chance to drop item: (128/chance)*100
Chance to drop unique item: 0.29%.

You have a 0.0001423% (1 in 699406) chance that the monster will drop a unique tier 5 war sword. But we're not concerned about uniques:

Base chance: chance = 60 - (82-77)/5 = 59 (= 16.95% chance w/o MF)
Multiplication for extra precision: chance = chance*128 = 7552
EMF is counted in: chance = chance*100/(100+35) = 5594
Comparison to itemtypes Min: if (chance < 2200) then chance = minimum
The treasureclassex bonus is 0 for regular monsters.
Percentage chance to drop item: (128/chance)*100
Chance to drop rare item: 2.28%.

You have a 0.001125% (1 in 88865) chance that the monster will drop a rare tier 5 war sword. Keeping in mind that you will probably kill about 5K monsters per Act, you can realistically find one with not too much difficulty.

By the way, if you're not specifically looking for a tier 5 war sword, you'll get one rare every 44 monsters. And only tier 5-6 stuff is nearly as rare - a tier 4 item is about ten times as common if not more, and a tier 3 item is much more common.

[Masterkilla]

Thanks a lot Laz!!!

[Zanzu]

Wow...i just learned more about drops in this mod then i ever hoped to know of, didn't even think i would learn about the chest drops and such. Very very useful, thanks alot

[DemonicAngel]

Trying to understand this whole thing

[quote=Brother Laz";p="320044"]
Sets
itemratio = 25
div = 5
minimum = 1500

If no set is available for the current item at the current mlvl, drop a double durability magic item.
[/quote]

Does this mean if it succeeds the chance to drop a set but is not in a 121 area, it will usually be a x2 durability magic?

[Brother Laz]

If the item rolls 'set' but has no set version or is not level 121, it will always downgrade to a x2 durability magic item.

[Xeraan]

IIRC /players4 adds three unpartied players, resulting in an exponent of 2.5, rounded down to 2. Or am I mistaken there?

[Keku]

So, what are the best possible scenario for getting a unique to drop?

[Arjento]

[quote=Keku";p="320722"]
So, what are the best possible scenario for getting a unique to drop?
[/quote]

Currently I'm farming Izual on Players 3.

Good exp and the odd Unique drop from here.

Although I'm noticing less chance of Unique and rare items everytime I reload the game...is this how it's supposed to be?

BTW, GREAT list Laz, very informative.

[Brother Laz]

[quote=Keku";p="320722"]So, what are the best possible scenario for getting a unique to drop?[/quote]

Urns. Seriously.

[Keku]

Urns. Seriously.

On players/8? How much MF would you need to get a high percentage? Which areas?

[Brother Laz]

I posted this thread so I wouldn't have to answer questions like this myself. As for area, I suggest you choose an area with urns. Players whatever floats your boat, define 'high' percentage, and search for '16.67%'.

[Keku]

I posted this thread so I wouldn't have to answer questions like this myself. icon_wink.gif As for area, I suggest you choose an area with urns. Players whatever floats your boat, define 'high' percentage, and search for '16.67%'

So, wait, does an urn have a 16.67% chance to drop a unique, or just an item? I'm getting mixed signals...

[D2 MOD player]

Wow. Very interesting post. It's gotten rid of a few myths on drops. For instance: many players state it's based on character level. If so it's only indirectly. Monster level is often similar to your character level in D2 or you get your but kicked. But it opens the strategy to rush through the game (something I've never liked doing) and getting to those higher level drops. Even if your character level is lower you should get the same drops as someone who went through the game normally (except the drops will be slower because your a low level and not as powerful).

Also concerning urns. I've always liked kicking things in this game. Anything I can't do in real life without paying for colateral damage is fun in a game. We're all just a bunch of vandalists at heart aren't we?

[Maxx Power]

For the record if you've already found the base item type of the item you want to make a unique out of, and that item happens to be sacred, then you're much better off attempting the Chaos reroll recipe (Item + Brilliant Arcane Shards + Healing Pot + Mana Pot), which gives you a 0.17% chance at a unique and 3.93% chance at a set, which are much better odds than anything you'll find in the field.

[Karb]

I posted this thread so I wouldn't have to answer questions like this myself. icon_wink.gif As for area, I suggest you choose an area with urns. Players whatever floats your boat, define 'high' percentage, and search for '16.67%'

So, wait, does an urn have a 16.67% chance to drop a unique, or just an item? I'm getting mixed signals...

16.67% chance for the dropped object to be an item. Keep in mind an urn will roll for 6 objects when you crack it (but only 20% of them do contain something)!

[D2 MOD player]

But in some areas there are many more urns then chests. I do remember in the past when playing, sometimes those areas are very profitable. Areas with many chests are great too like Kurast.

[Woodsplitter]

The act 2 tombs have loads of urns. Absolute tons. I've gotten plenty of items from going through those places, as well as gold. Just run all 6 Tal Rasha tombs.

[Keku]

16.67% chance for the dropped object to be an item. Keep in mind an urn will roll for 6 objects when you crack it (but only 20% of them do contain something)!

So if it rolls an item, what's that chance for that item to be a unique/rare/magic?

[Keku]

Oops, internet is acting up. Sorry for double post.

[Brother Laz]

[quote=Keku";p="320937"]So if it rolls an item, what's that chance for that item to be a unique/rare/magic?[/quote]


That's what this guide is for. Follow the steps I spent 5 hours researching and writing.

[Karb]

16.67% chance for the dropped object to be an item. Keep in mind an urn will roll for 6 objects when you crack it (but only 20% of them do contain something)!

So if it rolls an item, what's that chance for that item to be a unique/rare/magic?

It depends on your MF. You'd have to use the calculations found at the top of the first post to find out.

[Keku]

That's what this guide is for. Follow the steps I spent 5 hours researching and writing.

Well, I did ask for you do it for me when first posted in this thread...

[D2 MOD player]

Yes, it is true that some of it can be a bit difficult to understand but he actually spends time stating what some of the acronyms mean, so it's not totally inaccessible by people who can't remember all that. Even if you can't fully understand it, it does explain enough to get the idea of what's going on and visualize at least a basic mapping of how that item dropped. It tells you how much magic find helps, something I've always wanted to know. As long as you do the math and take a few minutes.

[Zanzu]

[quote=Brother Laz";p="320977"][quote=Keku";p="320937"]So if it rolls an item, what's that chance for that item to be a unique/rare/magic?[/quote]


That's what this guide is for. Follow the steps I spent 5 hours researching and writing.[/quote]
LMAO...poor Laz, he places it all out in black and white for us but still people can't understand it and have to ask him for help. lol

[Masterkilla]

That's what this guide is for. Follow the steps I spent 5 hours researching and writing.

Well, I did ask for you do it for me when first posted in this thread...

Have you no respect at all?
He spent so much effort writing something for you and you complaining that it's too (apparently) long to read?
And when he tells you to just read it you say you asked him to in the first place?
I have nothing more to say on this.... some people absolutely amaze me....