From FFXI Wiki

Resists lower magic damage and/or duration of offensive magical spells, abilities, and weapon skills, and occur more frequently the lower the caster's Magic Hit Rate is. Under normal conditions, any spell that does damage can be resisted in these increments:

Resist Level 0: 1/1 (No resist)
Resist Level 1: 1/2
Resist Level 2: 1/4
Resist Level 3: 1/8 (Full resist)

Additionally and unrelatedly, Magic Damage can be reduced by other factors, like target-specific magic damage reduction, Magic Defense Bonus, and target-specific elemental resistances.

Current Theory

Magical effects have a certain number of "Resist" states (as shown above for damaging magic). For some spells (like Sleep) a resist will affect duration. For others (like Elemental Magic) it affects damage.

Magical effects do not always have a full range of resist states. Some (again, like Sleep) only have Resist Level 0 (60 second duration) and Resist Level 1 (30 second duration).
Thus, the odds that you will successfully land Sleep on a monster follows the Two-State relationship on the left below. This means that you have a 99.75% chance of initially landing Sleep on a monster with capped Magic Hit Rate, but still only a 95% chance of landing it for the full duration, as shown on the graph to the right.
All Enfeebling effects with fixed duration follow this Two-State relationship. Other magical effects such as enfeebling effects without set duration (like Paralyze) or spells that have neither damage nor enfeeble effect (like Dispel).
There is insufficient testing/information to prove if there are multiple resist states or the exact determination of durations. Spells with a damage and enfeeble component calculate resistance and states independently for damage and enfeeble duration.

M resists States.jpeg
Resist state distribution.JPG
Relationship between Magic Hit Rate (X)
and Effect Land Rate (Y)
Relationship between Magic Hit Rate (X)
and Resist State Probability (Y)

These relationships were discovered through testing, which indicated that Magical Resist state is determined by an iterative process. So when you cast a spell, you have a certain Magic Hit Rate against the monster. The game generates a random number between 0 and 100% and compares it to your Magic Hit Rate. If the game's random number is higher than your Magic Hit Rate, you move up one Resist State and the game generates another random number to compare. So if it is higher than you once, you gets a 1/2 resist. If it gets higher than you twice, you get a 1/4 resist. If it gets higher than you three times, you get a 1/8 resist. If the spell you cast only has two resist states and the game beats your magic accuracy twice, then you just get a "___ resists the effects of ____."

This results in the following distribution of Resist states for magical damage:

This results in the following distribution of Resist states for 2 state enfeebles:

Roll Analogy: It's somewhat classic in FFXI probability to liken everything to a /random battle, so here goes!
Imagine that every time you cast a spell you're having a /random battle with the monster. Your "/random" is always equal to your magic hit rate × 1000, so a 95% magic hit rate would be a 950 roll. If the monster loses his first roll, your spell lands unresisted. If he wins his first roll, he gets to roll again. The number of times he wins determines the Resist Level as listed above. So two wins would be Resist Level 2, a 1/4 resist. Two wins against Sleep or Sleep II would be a full effect resist, because those spells only have a Resist Level 0 and 1.

Magic Evasion

Every player, monster, or pet has a magic evasion stat, which is compared to their foe's magic accuracy when a magic effect targets them, whether that be a magical attack, an enfeeble, or a debuff from an additional effect. Magic evasion is separated into nine types; a hidden base magic evasion stat, and eight elemental magic evasion stats that use base magic evasion as a baseline.

Base magic evasion depends on level, job traits (including Gifts), buffs, enfeebles, and magic evasion from gear. Magic effects without an element are compared to this stat to determine magic hit rate.

Elemental Magic Evasion

Elemental magic evasion consists of the eight magic evasion stats used against magic effects that have an elements. These are based off of base magic evasion, then modified by buffs, enfeebles, elemental resistance from gear (for players), and resistance rank (for monsters and summons; see below). Sometimes they are the same as base magic evasion, especially for players, but sometimes they are not. It is thought that a difference of 1 elemental resistance, as seen on the gear screen, corresponds to 1 point of magic evasion for that element, but this has not been proven.

In addition, modified elemental resistance from baseline also causes several effects for players, regardless of the magnitude of the change in resistance.

  • Positive elemental resistance (as seen on the equipment screen) enables an additional resist state (level 3 for magical attacks, varies for enfeebles).
  • The additional resist state is not guaranteed, and sufficient magic evasion to fully resist an attack is still required.
  • Negative elemental resistance (as seen on the equipment screen) prevents full resists to that element regardless of magic accuracy and magic evasion (barring Resist Status job traits and equipment bonuses).

Resistance Rank

Resistance ranks are a tiered system representing the relative elemental resistances of a monster. Each monster has a resistance rank in each of the eight elements, which impacts elemental spells and effects used on them. Each family of monster (including sub-families, such as mosquitoes within the bee family) have their own fixed set of resistance ranks. Notorious monsters can also have their own specific set of resistance ranks, independent of their base family's ranks. A higher resistance rank is represented by a lower percentage. The following chart shows the different possible ranks, which are represented as percentages due to their relationship with skillchain damage:

Resistance Ranks
(Low resistance) 150% 130% 115% 100% 85% 70% 60% 50% 40% 30% 25% 20% 15% 10% 5% (High resistance)

Resistance ranks effect many aspects of elemental effects used on them.

  • Resistance ranks are proportional to the magic evasion a monster has towards an element, so for a given monster, a higher resistance rank means they have a higher base magic evasion stat towards that element. For example, Leeches' least resistant element is normally light, corresponding to a rank of 150%, while their most resistant element is water, corresponding to a rank of 50%. If a monster's resistance rank is temporarily decreased, their magic evasion to that element is also lowered.
  • This does not mean that monsters with a higher resistance rank automatically have more magic evasion for that element than monsters with a lower rank. Level, job traits, buffs, and debuffs all affect how much magic evasion a monster has.
  • Some monsters can change their resistance ranks mid-battle.
    • Monsters that absorb an element, either normally or due to a trigger, always have their absorbing element have their lowest resistance rank.
  • The exact formula for elemental magic evasion based on resistance rank is currently unknown.
  • Resistance ranks force certain behaviors on magic hit rate for spells and effects of that element when they are high enough. This includes offensive spells, enfeebles, and debuffs from additional effects.
  • At ranks of 15% to 50%, an additional resist state of 1/2 is forced onto any magic effects that are used on them. This brings resist level 0 to 1, 1 to 2, 2 to 3, and 3 to a special resist level of 4 (1/16th damage). As such, it is normally impossible to land anything for better than 1/2 damage on a monster with a 50% or higher resistance rank to that element.
  • At a rank of 10%, in addition to the additional resist state listed above, magic hit rate is automatically floored on them regardless of magic accuracy.
  • At a rank of 5%, all magic effects are forced to be resist level 4, regardless of any other factors.
  • Resistance ranks determine skillchain element and damage.
  • Skillchains that consist of multiple elements automatically hit the element that corresponds to the monster's lowest resistance rank. For example, if Distortion (ice/water) is used on a standard Tiger (100% ice, 130% water), it will deal water-element damage, and will be affected by modifiers that affect water damage, such as weather. In the case of a tie, the the element is chosen in the following priority order:
    Element: FireElement: IceElement: WindElement: EarthElement: ThunderElement: WaterElement: LightElement: Dark
  • Skillchain damage is multiplied by a monster's resistance rank after all other factors. For example, with no other modifiers, a closing Weaponskill that deals 1000 damage and results in Compression will deal 500 damage to a monster with a Darkness rank of 100%, 250 damage to a monster with a Darkness rank of 50%, and 750 damage to a monster with a Darkness rank of 150%.
  • Resistance ranks modify the damage bonus that Magic Bursts give, by amounts given in the following table:
Resistance Rank: 150% 130% 115% 100% 85% 70% 60% 50% 40% 30% 25% 20% 15% 10% 5%
Magic Burst Damage Bonus: +150% +115% +85% +60% +50% +40% +15% +5% +0% +0% +0% +0% +0% +0% +0%
  • This is additive with the normal +35% damage bonus that magic bursts give. For example, on an enemy with a resistance rank of 115%, the magic burst would give a damage increase of 35% + 85% = 120%.

Modifying Resistance Rank

There are several ways to lower resistance ranks. All methods that lower resistance ranks cannot bring it lower than 150%.

  • Skillchains temporarily lower the target's resistance ranks for each of the skillchain's elements by one stage for the duration of the magic burst window.
  • This resets after the window ends or another skillchain is executed, replacing the effect with the elements of the new skillchain.
  • Rayke temporarily lowers the resistance rank by one stage for each corresponding rune expended. For example, using Rayke with three Ignis runes will lower the target's fire resistance rank by three stages.
  • Subtle Sorcery allows the user to ignore the extra resist state from the target having a 50% or higher resistance rank when using Elemental Magic.
  • It does not change the actual resistance rank.

Status Effect Resistance

  • Resist [Trait] works on a 1:1 basis against normal mobs and on a 2:1 basis against notorious monsters.
    • In other words, each point of a status resist via either a trait or gear is a direct 1% chance towards a special "Resist!" for that status effect against a normal monster and who's efficacy is halved against any and all notorious monsters.
    • Resist [Trait] gained from food does not seem to follow this rule and is not reduced against notorious monsters. Confirmation is needed.
    • The cap for "Resist!" is 90%.
      • +90 stacked Resist [Trait] for normal mobs and +180 for notorious monsters.
  • "Resist All" covers a rather large number of status effects (some of which can only be obtained via gear). See below for resist [trait]s / status effects covered (and not covered) by "Resist All":
  1. Heraldic Imp's "Abrasive Tantara"
  2. Dynamis San d'Oria NM "Charm" and Inimical Corse's "Danse Macabre"
  3. Inimical Corse's "Envoutement" and Apex Bhoot's "Curse"
  4. Enigmatic Vampyr's "Eternal Damnation"
  5. Bard monsters in Ra'Kaznar Inner Court
  6. Apex Umbril's "Necrotic Brume"
  • Does not work
    • Bio
    • Death
    • Dia
    • Doom** - "Mortal Ray" from some types of Taurus including Aestutaur in Abyssea - Vunkerl.
    • Elemental debuffs
    • Flash
    • Lullaby
    • Nightmare - (HTMB Diabolos' Nightmare on Normal) (Resist Sleep does not seem to help either. However, Monberaux's Mix: Insomniant DOES block this. Chat log simply says he's "afflicted with Bio.")
    • Requiem
    • Terror
  • Unknown/Untested
    • Nocturne - via Resist Slow / Addle?
    • Repose - assumed not since Resist Sleep doesn't work

Status Effect Resistance via Bard Songs

  • Bard songs such as Operetta, Pastoral, Aubade, Gavotte, Capriccio, Fantasia, and Round all provide "Resist!" traits. It is unknown whether or not a magic evasion bonus is given like with bar-spells.

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