Magic Resistance WoW.

[Saidus[V]]

When hit by a spell, you have two chances to resist the spell. The first chance is based on your level. If you are much higher level than the attacking caster, you will have a significant chance to resist the caster's spell, but if you are much lower level, you will have a minimal chance to resist the spell (minimum of 1%). If you make this resistance chance, you are completely unaffected by the spell. The second chance to resist is based on your resistance score and the level of the caster. The higher your resistance score in relation to the level of the attacking caster, the higher your average resistance percentage, up to a maximum of 75%. Against most spells, this resistance percentage is the straight % chance to completely resist the spell. Against direct-damage spells (spells that deliver their full damage upon impact, such as Fireball, Mind Blast, and Earth Shock), this resistance is the percentage of damage you will resist on average.

When you are hit by a direct-damage spell, you have a chance to resist 100%, 75%, 50%, 25%, or 0% of the spell's damage, depending on your resistance score in relation to the level of the attacking caster. Your average percentage of damage resisted is the weighted average of your resistance percentages for each level of damage resistance (100%, 75%, 50%, 25%, and 0%). Using, as an example, a fire resistance score of 250 vs. a level-50 mage's fire spell, you would on average resist roughly 75% of the damage of that spell (as can be deduced by calculating the weighted average for the corresponding column in the example table below). To further the example, if you had fire resistance of 100, you would, on average, resist roughly 30% of the spell's damage.

Here is an example of how various resistance scores play out against level-50 spells: