Mechanics of Magic Find and Loot Tables

Discussion in 'Guild Wars 2' started by Karasu, Sep 21, 2012.

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    Karasu Community Member

    Mechanics of Magic Find and Loot Tables
    Disclaimer: Everything in here is pure theorycrafting on my accord, based on different games and
    some communication with devs. All values are only chosen to help demonstrate the examples.

    Loot Table

    Before you can understand Magic Find it's important to know how Loot Tables work. Many games use a very similar system, for example Diablo III.

    First the game checks if you are going to receive an item. Sometimes this guaranteed such as with chests, otherwise it's random like you'd have with mobs. Mobs that spawn infinitely such as you'll find at the start of the Ascalon Catacombs Explorables have their drops disabled to counter farming, also critters. There is a participation requirement such as two hits on a mob for each kill to count. A higher monster rank (veteran, champion, legendary) also slightly increases rewards.

    If an item will drop there is a series of choices that need to be determined. Step by step each property of the item is chosen. For example the first roll would be the type of item: Equipment or Materials. For example:
    • Equipment 40% chance, Materials 30% chance, Junk 30% chance
    • In order, a roll is made on equipment. A failure creates a second roll in this table for materials. A second failure here will default to generating junk.
    Each time a choice from one table is determined the next is pulled up and the next property is rolled for. More realistic tables would look like:

    Initial: [Special, Armor, Weapon, Crafting Material, Trophy, Coins, Junk]

    Armor: [Chest, Legs, Helm, Shoulder, Gloves, Boots, Trinket]

    Skin: [World type 1, type 2, .. Zone type 1, type 2, .., Creature type 1, type 2, .. ]

    HasUpgrade: [Yes, No]

    Upgrade: [sigil/rune 1, sigil/rune 2, ..]

    Now all that's left to be determined are the attributes: level, attribute set and rarity.
    The interesting part here is the rarity roll, as it starts by rolling the highest valued items first :

    Legendary1/100000
    Exotic1/1000
    Rare1/100
    Masterwork1/10
    Fine1/2
    Basicrest
    *Made-up numbers for demonstration purposes

    Each table is required to have a 'remainder' option. That's why plants sometimes drop a Dandelion Blossom upon gathering. This means the roll on a dye failed and resulted in junk. I'm not sure if this dye drop is related to the crafting critical chance or magic find.

    Many of these tables are rolled in parallel. The order in which these items are rolled is very important in our next chapter on Magic Find.

    Magic Find

    Each player has a base percentage of 100% magic find which acts as a multiplier of 1 toward each roll. Magic Find can be increased trough specific equipment, upgrade components, food and buffs.

    For example you equip an Explorer's Chestpiece of the Traveler with +3% (Explorer) and +7% (Rune) and eat Strawberries and Biscuits giving you an extra +10%. Your new magic find is now 120%.

    With nearly every roll in the loot table this multiplier is applied on the roll. If you would have 200% magic find an item with a chance of 1/1000 would increase to 2/1000. Because the rarest item is rolled first the relative chance of each tier stays the same, but you'd have a skewed increase in each chance in favor of the first items.

    Item A has 10% chance, item B has 20% chance. Because each roll is executed in sequence and dependent on the previous the global chance of rolling item A is 10%, but for item B it's 0.90 * 0.20 = 18% chance.

    Now we apply a magic find multiplier of 2 by equipping an extra 100% MF. Item A : 20%, Item B : 40%. Global chances still are the same for our first item in the row, but the second item becomes 0.80 * 0.40 = 32% chance. Instead of a 100% increase we now see an increase of 77% toward the global chance of item B.

    Another really important thing to note is that, because Magic Find is based on percentages you have diminishing returns: every extra MF you apply will be less efficient than the previous.

    Say you carry +90% MF for a total of 190%. If you want to double your magic find, a 380% total, it will require an extra +280% MF!

    Eventually Magic Find boils down to: how much are you willing to sacrifice to improve your drops? Keep in mind that less damage also means killing mobs slower.
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    Karasu Community Member

    Affected by Magic Find

    I've had many people ask me if certain parts of the game were affected by Magic Find. Here's my reasoning behind some of the answers:

    Confirmed parts include the rarity of a dropped item, the chances on material drops and certain special world drops.

    Probably not affected are:
    • Salvaging : The chances for recovery and critical success is detailed in the tooltip of salvage kits already. There also used to be a salvaging bonus on certain runes. It's unlikely magic find would interfere with another clearly indicated stat.
    • Crafting critical success : Same reasoning as with the salvage. For crafting there is already a different stat that can only be found with the boosters from Black Lion Chests.
    • Gathering critical success : With gathering each tool has the same critical success chance such as hidden stashes for trees, dyes for plants and orbs for mining. Also the chance on receiving 2x that material. Master tools and Black Lion tools - also obtained from the chests - increase this critical chance. Note that Master tools can only gather up to Tier 3/4 materials.
    • Mystic Forge : The randomness of the forge is already a very critical parameter. Any bias that can be influenced by the player would not be a healthy mechanic.
    Overview of Magic Find items and effects

    - / -
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    Karasu Community Member

    Anti-farm code

    Certain mechanics are solely in place to prevent abuse and certain behavior of players.

    Confirmed Implementations

    Bonus Experience
    Bonus experience is granted based on the time the mob has been alive. This nudges players to refrain from staying in one location. Up to3x (?) as much XP can be gained this way. A mob's lifetime possibly also affects the quality of drops.

    Lootless Mobs
    When there's a source of near infinite mobs, all experience and loot is disabled on these to prevent endless farming. Many dungeons and dynamic events are affected by this.

    Dungeon Tokens
    The main reward for playing trough dungeons are Dungeon Tokens. Each first completion of the day of one of the explorable modes grants 60 tokens. Other runs of that path that day will only give 20 tokens.

    Dungeon Gold and Experience
    Recently a new mechanic was introduced to discourage farming the same path of a dungeon. The base reward for completion is 26 silver and 70% of the character's level progression. Now, that reward is reduced by 50% for a second completion within the hour, 75% for a third, ... The multiplier is 0.5^(N-1) with N the amount of times you completed that path in the last hour. Alternating paths is the solution for this.

    Repeating Dynamic Events
    Also a new anti-farm code : In PvE, the experience, gold and karma rewards for a specific (set of) dynamic event(s) start to lower after a while. Probably similar to dungeons the reduction is related to the amount of events over time. Since every event rewards a % based on your level it should be possible to alternate zones and gain the same rewards.

    Transfer Limits
    Your status as far as chests and crafting nodes go are saved per server. Hopping servers allowed players to continuously farm jumping puzzle rewards and orichalcum ore / orrian saplings at a much higher rate. Instead of 4 hours per node and 24 hours per chest. Now, there is a limit of one transfer per 24 hours to counter this abuse. It is unsure how guesting will account for this.

    Speculated Mechanics

    Group Bonus
    In Guildwars the amount of drops were affected by the amount of actual players in your party. Certain items like rares aren't affected.

    Killing speed
    Another technique is to lower the amount of drops if you're killing enemies too fast. This is generally to prevent single spike builds, think of Raptor Farming in GW.

    Accessibility
    Mobs that are close to the entrance of an area or a waypoint give less reward because they're easier to hop to. Instead of this, I expect that the actual mob placement and waypoint costs will account for this.
    ~Fin~
    Questions, remarks?

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