Repost of old thread, no changes to the guide, but I will include some additional info in post 2.

Basic guide to how MF works.
This is a fairly simple guide to try to clarify some of the confusion surrounding MF% ages and what they do. If you read nothing else here, read points 4 and 5 in the summary at the end.

What does Magic Find do?
Magic find increases the chances of a dropped item being of a higher magical quality.

What does Magic Find NOT do?
Magic find has no effect on the base item that drops, nor does it have any effect on whether the item is superior, normal, inferior, socketed if a white / grey item is selected, or Etheral. Because MF has no effect on the base item selection process it also has no effect on rune finding.

The Basic drop mechanics
When an item is dropped in D2 it goes through a multi staged selection process before it is actually generated. I will not go through the mechanics of the base item drops here. We are only concerned with what happens to the item after it has been selected that one will drop. It is however relevant to Magic Finding that the only way to increase the chance of an item being generated when a monster is killed is by having more players in the game.

The item quality selection process
We know an item has been selected to drop.

The game now has to decide what magical properties the item will have, if any, and so it goes through the following selection process which is done in turn for each item assuming it is relevant (clearly not applicable to runes, potions, gold etc).

1) Roll to check if it is Unique item (Gold). If this fails* then
2) Roll to check if it is a Set item (Green). If this fails* then
3) Roll to check if it is a Rare item (Yellow). If this fails then
4) Roll to check if it is a Magic item (Blue). If this fails then
5) Generate a White item with some of the following properties: Superior/Normal/Inferior/Sockets.
6) All items will finally go through a check to see if it is Etheral. Note that items which are indestructible cannot also spawn ethereal unless they specifically always spawn ethereal as is the case for certain uniques.
7) Drop the final outcome.

*There are times when this check will pass, but there may not be a unique or set item available. Instead of carrying on to the next check the game generates a �failed unique� or a �failed set� item. This results in a triple durability rare item for failed uniques and a double durability magic item for failed sets.

The order of this selection process is vital. I will come back to that in the summary.

So, how does Magic Find work?
Items always have a chance of passing any the check rolls above.

However, Magic Find increases the chance of making each of the quality checks in turn.

Magic find increases the base chance of making the quality check by the Effective Magic Find percentage for each quality. The effective MF percentages for each item quality are:

Effective MF for Unique items (Gold) = (MF*250)/(MF+250)
Effective MF for Set items (Green) = (MF*500)/(MF+500)
Effective MF for Rare items (Yellow) = (MF*600)/(MF+600)
Effective MF for Magic items (Blue) = MF

This means that the relationship is not linear, and if you fancy sticking the above into Excel and make a graph you�ll see just how non linear the relationship is. Here is a small table to give you the idea:

-------Effective MF %
MF%---Unique---Set-----Rare-----Magic
--10---- 9.62---- 9.80---- 9.84-----10.00
-100-- 71.43--- 83.33--- 85.71-- 100.00
-200-- 111.11- 142.86- 187.50-- 200.00
-300-- 136.36- 187.50- 200.00-- 300.00
-500-- 166.67- 250.00- 272.73-- 500.00
1000- 200.00-- 333.33- 375.00- 1000.00
Unlimited-250.00-500.00-600.00-Unlimited

This is the famous diminishing returns curve that is so often mentioned where the higher your MF % the more you have to add to achieve any marked improvement for Uniques in particular.

Summary
1. You do not need any added MF to find Uniques. There is always a chance.
2. Added MF increases your chances of upgrading the items that drop.
3. For uniques in particular we can see that the amount of help we can get from MF is restricted (severely), so killing things quickly becomes more important than adding more MF%. For example going from 500-1000 you gain comparatively little in terms of effective MF for generating uniques, but you will probably ruin any chance of killing things quickly if at all in Hell.
4. Because of the order the game checks for quality of items, more MF always gives a higher chance of rolling unique items.
5. Because of the order the game checks for quality of items, the only things that actually go down as MF goes up are White / Gray items.
6. When hunting socketables reduce your MF.

I will not claim to be the originator of any of this information. It is merely a simplified summary of the various guides and discussions I have read. In particular GTAMaloy]�s �Guide to all that is items" is a very worthwhile read hosted at Baron's Bazar, B-net, The Amazon Basin etc.[/QUOTE]

Additional information from the various posts in the original thread:

More players in the game = more drops, not "better" base item drops:





Treasure Class Basics
Follows on from a couple of questions from Lifeaintfair.



Finally:
The what if there are more than one unique to chose or the monster is not high enough level questions answered:



New ladder, old information, but hopefully useful to new readers.

Nice work
hopefully it helps some of the noobs

so 250 is the best mf% for uniques ?

Not at all, more is always better than less, it's just that it's not as much better as you might think.

You have to distinguish between actual MF on your character, and effective MF applied to the drops.

250 is the absolute maximum effective mf that can be applied to uniques, though you would need much, much more actual MF than is possible.

If you look at the different formulae, you will see that the factor of 600 for rares, 500 for sets and 250 for uniques are used to create a curved function. As you get to infinity, this is the maximum number you would end up with as well for each.

This post was edited by AyeCaramba on Jun 24 2008 10:09am

why is this not sticked?

looks good dude.

hopefully people will take the time to read it. lotta misinformation out there.

just as good as the original, now with more info bits. Gotta have my info bits.

Feel free to post a link to the item generation tutorial here if you have one to hand Morph. It would complete the lesson for anyone who might be interested in the finer technical points.

Bump