Oblivion:Reflect Spell

Reflect Spell is an M% chance to reflect a hostile spell back at the caster and avoid its potentially damaging effect. This means that having 100% Reflect Spell will make you invulnerable to magic while all hostile spells cast at you will bounce back at their casters.  The spells reflected count as though they were cast by the player for the purpose of spell leveling.
Notes
This effect can be gained for spell making via spells or the Shezarr Stone Doomstone.
Reflect Spell only protects you against spells cast by spellcasters, unlike Spell Absorption.  Therefore, it won't protect against damage from objects such as Magic Traps.  Fortunately, this means that it won't prevent you from reaping the benefits of good spells, such as the Arena Basin and blessings at altars, unlike Spell Absorption.
Sometimes it's really amusing to see goblin shamans fainting in front of you as they cast their Paralysis spells, will-o-the-wisps casting Absorb Health and transferring their own health to you instead, Wraiths cursing and silencing themselves as they attempt to weaken you, and so on.
Some creatures cast spells to which they themselves are immune. For example; atronachs, ghosts, and wraiths will resist Frost Damage, which is part of their Silence of the Grave spell--but they will still silence themselves, nevertheless. Reflecting the spell in this case still protects the player from harmful magic effects, but does not damage the attacker.
If an Absorb spell is reflected, both the source and target are reversed; e.g., if your Absorb Health spell is reflected, it will transfer health from you to your intended target.
It doesn't matter whether you're hit with spells cast by hostile or by friendly creatures; Reflect Spell will respond to everyone and everything likewise. It could cause trouble, accidentally harming or killing your allies. Beware!
Spells will only reflect once. If your spell bounces against an enemy back to you, no amount of spell reflection is going to bounce it back.
Likewise, reflected spells cannot be absorbed; even a player with 100% spell absorption can be hurt by his or her own spell that has been reflected back. Unlike both the previous examples, however, 100% resistance will remain fully functional.
If an 'On Target' spell reflects, it takes effect against the caster immediately; the projectile doesn't "bounce" off the original target.
Custom enchantments are not possible with Reflect Spell. This effect is disabled at the Enchanting Altar.
Here are some worthwhile items to acquire if you're trying to achieve a high spell reflection:
Mundane Ring has 35% Reflect Spell, next to 50% Resist Magic, but it is a random item and therefore can be hard to obtain. (If you are at least level 22, Raven Camoran will always be wearing this ring when you kill him in either of his associated quests.)
Spell Breaker is a shield with 30% Reflect Spell that you get for completing Peryite's Daedric quest, which can be started at level 10.
Ring of Sunfire can provide up to 25% Reflect Spell and 35% Resist Disease, but only if you get it at level 25 or higher.
Ayleid Crown of Nenalata can provide up to 25% Reflect Spell, but only if you get it at level 25 or higher.
Thorn Shield  can provide up to 22% Reflect Spell and 23pts Fortify Block, but only if you get it at level 30 or higher. It is obtained as a reward for the Shivering Isles quest To Help A Hero.
Amulet of Reflection provides 20% Reflect Spell; it is a random item and can be found starting at level 9.
Shield of Animus and Shield of Mirrors each provide 20% Reflect Spell; they are also a random item and can be found starting at level 22.
Shield of the Crusader from the Knight of the Nine plug-in can provide up to 18% Reflect Spell, but only if you get it at level 21 or higher.  It is obtained at the end of Wisdom of the Ages. You also must have 1 infamy or less to equip it.
Cursed Aegis of Reflection  and Cursed Mercury Shield  provide 18% Reflect Spell but also Drain Magicka 10pts; both are random items and can be found starting at level 8.
Spellturn Cloak from the Unearthing Mehrunes Razor plug-in can provide up to 15% Reflect Spell, 15% Resist Magic and 15pts Spell Absorption, but only if you get it at level 20 or higher.
Ring of Mind Shielding  can provide up to 12% Reflect Spell and 12% Resist Magic, but only if you get it at level 25 or higher. It is a reward for Everything In Its Place quest.
Ring of Namira is an unleveled ring with 10% Reflect Spell and 12% Reflect Damage that you get for completing Namira's Daedric quest, which can be started at level 5.
Amber Armor Shield  can provide up to 10% Reflect Spell; but only if you get it at level 23 or higher. It is obtained as a reward for the Shivering Isles quest The Antipodean Hammer.
The Heart of Spell Turning (Gatekeeper Gift)  has a Reflect Spell effect which can be acquired during the main quest Rebuilding the Gatekeeper, choose the Heart of Spell Turning body part when selecting parts for the new Gatekeeper. You can only have one Gatekeeper Gift Power at a time.
The Manipulate Weather greater power  has a 5% chance of bestowing the Torrent ability, providing 30% Reflect Spell.

See also
Sections:
Reflect vs Absorb vs Resist: Information on the similarities and differences between these effects. 

Related effects:
Spell Absorption, Resist Magic, Weakness to Magic
Reflect Damage
Shield, Fire Shield, Frost Shield, Shock Shield

Alchemy Ingredients
The following alchemy ingredients can be used to create a potion of Reflect Spell: