... Magic

The beginners guide to Magic

There are six schools of magic used in The Elder Scrolls: Secret Stories, Alteration, Conjuration, Destruction, Illusion, Mysticism, and Restoration. Every spell belongs to one of these schools, and your ability to cast a given spell is determined by your skill level in that school. The seventh magical skill is Alchemy, which allows you to create your own potions and poisons.

Spells
Spells are widespread and easy to acquire. Although the easiest spells can be cast by even beginning players, advanced spells require skill and Intelligence: casting a spell consumes Magicka, and spells can only be cast if your skill level in the spell's school is sufficiently high. To acquire spells, you can purchase them from Spell Merchants. You can also create your own custom spells.

A list of spells can be found here and here.

Powers
Powers are similar to spells, but they cannot be purchased or created. Several powers are bestowed upon characters based on race and birthsign; others can be obtained by visiting Doomstones, becoming a vampire, or completing certain quests. There several important differences between Spells and Powers:

• Skill level in the respective school of magic does not count against a power. A novice of Illusion, for example, can cast Lover's Kiss or Jone's Shadow despite the fact they contain Illusion spell effects that no novice could otherwise employ. The magicka cost of a power is not affected by skill level.
  
  
• Armor does not lower the Spell Effectiveness of Powers. This is one reason The Lord birthsign is advantageous to warrior types: it bestows a strong healing spell that retains its full effectiveness despite whatever armor they may be wearing.
  
  
• Powers cannot be Silenced.
  
  
• Some powers like the Vampiric Power Reign of Terror cannot be reflected or absorbed (but can still be resisted) by enemies, which makes them invaluable when fighting enemies that reflect/absorb spells.
  
  
• Powers come in two varieties: Greater Powers and Lesser Powers.
  Greater Powers can only be cast once a day, but cost no Magicka when you invoke them.
  Lesser Powers usually have a Magicka cost (with the Khajiit's Eye of Night being a notable exception), like spells, but they can be cast as often as those Magicka reserves permit.

One disadvantage of powers is that casting them does not contribute any experience points towards your magic skills.

A list of powers can be found here.

Abilities
Abilities are magical effects that are permanently (or nearly permanently) active on your character. The most common abilities are those associated with races, birthsigns, and vampirism.
A critical difference between Abilities and any other type of active effect is how Fortify and Drain effects are implemented. Modifications from abilities alter the base value of the associated quantity (Health, Magicka, Fatigue, Attributes, or Skills) -- whereas all other Fortify and Drain effects only alter the current value of the quantity. Implications of this difference include:

• Fortify effects from abilities do not make the quantity appear in green in your Journal Stats; Drain abilities do not make it turn red.
  
• For Fortify Skill abilities, you obtain any skill mastery perks from the skill increase.
  
• Fortify Alchemy abilities do increase the strength of any potions you make.

If your character has lost all of his/her abilities, you have probably been affected by a bug that can occur during the Molag Bal quest or if you use Sheogorath's Protection. Details are provided in the quest page Bugs section.

Diseases
Diseases are magical effects that remain active on your player until cured using Cure Disease. Diseases are carried by various animals, undead, and NPCs. You can become infected with a disease if you are struck by an infected creature.

Scrolls
Scrolls can be purchased from some merchants or can be randomly found in loot; it is not possible to make your own scrolls. Anyone can use a scroll, regardless of magic skill, and casting a scroll does not use any Magicka. However, each scroll can only be used once. Also, using a scroll does not provide any magic experience.

Magic in Combat and in the Elder Scrolls: Secret Stories
Destruction magic is a powerful tool, but a dull knife wielded in certain hands is more deadly than a Daedric weapon wielded by an idiot. Likewise, the enterprising mage must make certain decisions. Fighters and thieves are advised to use magic to augment their abilities rather than cause damage; those with such leanings do not need to face many of the following decisions. Also remember to only use a level magic that is logical for you character to use based on race, birth sign and so on both in combat and out of combat.

For more information please visit this link and the Unofficial Elder Scrolls Wikia.