Resistance

Category:Terminology
Resistance is the weakening of the effect of a magical attack due to natural or aided elemental resistance. When a magical attack occurs, the game makes a random check of the Magic Accuracy of the attack against the target's resistance to determine how much the attack is resisted.
*Resisting magic damage causes the target to take 1/2, 1/4, 1/8, or 1/16 of normal damage.
*Resisting Status Effects reduces the duration of the effect, possibly negating it entirely.
*If a spell is resisted completely, you get the message "Target resists the spell."
**Or, if it is a peripheral (not direct) target of an AoE spell, "Target resists the effects of the spell!"
==Resistance rate==
Resistance is affected by many things:
*The target's elemental resistance stat.
**Most monsters have different resistance to different elements, so mages should try to use spells of elements that the monsters are relatively weak to.
**Players have base elemental resistance stats equal in value to the cap for C-ranked skills. These are the same stats shown in the Equipment screen. However, the Equipment screen only shows by how much your base resistance has been increased or decreased, not the base value of your resistance stats. For instance, a level 75 character would have hidden scores of approximately 225 (the cap for a C rated skill at 75) in his resistance stats, but the Equipment screen will still list them all as 0 unless they have been modified in some way (whether positively or negatively)
***It is, so far, impossible to determine whether the value for this stat is specifically C-, C, or C+. However, if one were to draw a parallel between the melee stats and magic stats, it is likely that it's C.
***Elemental resistance from equipment, Bar Elemental spells, and Threnody songs are added (or subtracted) directly to this stat.
***Elemental Ninjutsu and Ancient Magic lower elemental resistance by 30 points for 15 seconds.
***Threnody lowers elemental resistance by 50 points, plus 5 for each +1 on the instrument.
*MND increases resistance to White Magic spells as well as reducing their base damage.
**Some people believe that MND increases resistance to all spells, not just White Magic, but there are no known published tests that show this conclusively.
*INT reduces the base damage of Black Magic spells and Ninjutsu.
**Some people believe that INT also increases resistance to these spells, but again, there are no known published tests that show this conclusively either.
*CHR does indeed increases resistance to Bard songs and Charm. http://ffxi.crgaming.com/interviews/viewinterview.asp?Id=272 
*Resistance to Status Effects from Job Traits, equipment, or spells that provide the Bar Status Effect (such as Barsleepra) and songs such as Fowl Aubade.
*The elemental day and weather strengthen spells of the matching element and weaken spells of the element it is strong to.
*Many Notorious Monsters have higher resistance, or even immunity, to certain Status Effects.
*The Magic Shield effect causes the affected monster to completely resist all spells, but it does not affect non-spell magic damage (e.g. from Skillchains or Astral Flow).
*Dia, Bio and elemental Ninjutsu combine both direct damage and a debuff effect. With these spells, the direct damage can be resisted, but the debuff effect is never resisted (unless the target has Magic Shield on).