Oblivion:Dispel

Remove Magicka-based spell effects from the target.  Dispel can work to immediately cancel almost any magical effect that has a duration.  However, it only works when the source of the effects is a spell.  Dispel does not affect abilities, diseases, curses, or enchantment effects (either from weapons or apparel).  Dispel also does not appear to remove effects from potions or scrolls, only effects from cast spells.

In combat, it can often be hard to know whether a negative effect came from a spell, or whether the source was actually a poison, scroll, or lesser power.  For example, ''Spriggan's Curse is a Drain Luck effect, but since the curse is a lesser power rather than a spell, Dispel'' will not work to remove it.  Generally, if a creature's spell is listed as "Immune to Silence" it is likely to also be immune to Dispel.

The points are related to the maximum strength spell that can be removed by the Dispel spell.  This strength of a spell is the magicka cost (Magic Overview) of casting the spell, taking into account the caster's skill level (i.e., not the base magicka cost that are listed on the Spells page). The strength of a Dispel spell is 5 times its magnitude, meaning that a 50pts Dispel spell will dispel another spell with a strength of 250, but not one with a strength of 251. Legendary Dispel is the strongest Dispel spell available, and it can dispel spells with a strength up to 1250. For multi-effect spells, Dispel acts on all of the effects simultaneously, i.e. either all are removed, or none are removed.  Also, Dispel can remove effects from multiple spells at the same time.

In practice, it may be very difficult to predict what strength Dispel effect is necessary to cancel a given spell, because it is necessary to know your opponent's skill level.  The skill levels of NPCs are generated semi-randomly.  Although you can expect that a Bandit Hedge Wizard you encounter at high levels will have better magical skills than one you encounter at low levels, the method used to determine the actual values is unknown.

Notes
This effect can be gained for spell making and enchanting via spells or choosing the Serpent birthsign.
Dispel can be useful both on yourself and on enemies; it has been classified as a defensive spell because it is a non-hostile spell.
On yourself, you may wish to use dispel to get rid of effects such Absorb Attribute, Absorb Skill, Burden, Drain (Drain Attribute, Drain Health, Drain Magicka, etc.), Silence, Weakness (Weakness to Fire, Weakness to Magic, etc.). However, Dispel is not "intelligent" and will remove beneficial effects (including Conjured creatures) as well as harmful ones.
On enemies, you may wish to use dispel to get rid of effects such as Chameleon, Invisibility, Resist (Resist Fire, Resist Magic, etc.) Shield, Summon, Water Breathing, Bound Armor, and Bound Weapon (although not against Mythic Dawn agents, whose bound armor and weapon effects come from abilities). Combining Dispel with Calm ensures that enemy spellcasters do not re-summon anything, as casting Dispel will not break the calmed state, while unsummoning any creatures that have been summoned so far.
There are no Dispel poisons that you can use on enemies, only potions for use on yourself.
From Sigil Stones, Dispel can only be used against enemies.
Dispel is one of the enchantments available for making a custom mage's staff (it is also found on random generic staves).
Dispel can be added to custom "on Touch" spells to effectively create reflect-proof spells.  Adding Dispel on Self at the end of the spell will cancel the spell's effects if an enemy reflects the spell back at you; this can be particularly useful with high-level destruction spells.  The Dispel magnitude must be large enough to counteract the spell's other effects.  This technique only works with on Touch spells, not targeted spells, because it can take several seconds for a targeted spell to be reflected back. As normal though, the Dispel on Self component will blindly remove your own defensive spells and summons, whether the spell is reflected or not.
Casting any Dispel spell will increase your Mysticism skill, even if there are no active effects for you to dispel.

See also
Sections:
Options for Healing: Differences between all the various healing effects.

Related effects:
Restore Attribute, Restore Fatigue, Restore Health, Restore Magicka
Cure Disease, Cure Paralysis, Cure Poison

Alchemy Ingredients
The following alchemy ingredients can be used to make a potion of Dispel: