Dispel Magic removes magical effects from spells, potions and some magical items from everyone in its area of effect.
Despite what the in-game description says, levels of the magic being dispelled don't factor the dispel success rate, only level-differences among the casters count. This spell checks effects from different casters individually, meaning that effects received from a high level caster are less likely to be dispelled than those from a low level caster when all are present on the same person.
The target's Magic Resistance, if any, does not affect this spell, the only way to defend against it is Spell Immunity: Abjuration.
|“|| Dispel Magic|
A Dispel Magic spell removes magical effects upon anyone within the area. This includes effects given from spells, potions and certain magical items such as wands. It does not, however, affect enchanted magical items or spell protections such as Spell Turning and Spell Deflection. The chance of the dispel succeeding is determined by the level of the caster and the level of the magic being dispelled. The base chance of successfully dispelling is 50%. For every level that the caster of the Dispel Magic is above the original caster, his chance of success increases by 5%. For every level that the caster of Dispel Magic is below the original caster, his chance of success decreases by 10%. However, despite the difference in levels, there is always at least a 5% chance of success or failure. Thus, if a caster is 10 levels higher than the magic he is trying to dispel, there is only a 5% chance of failure. Similarly if the caster is 4 levels lower than the magic he is trying to dispel, there is only a 10% chance of success. Intuitively, this spell is almost useless if the target is 5 or more levels higher than the caster.
Note: While this spell dispels the individual effects of Grease, Web, Stinking Cloud, and other such spells, it does not dispel the area of effect.