The Elder Scrolls V: Skyrim/Magic

Alteration
Notes:
 * Ironflesh (and similar spells) have synergy with the cloak spells, allowing to inflict damage in melee without taking too much damage oneself.

Perks

 * Novice Alteration: Cast novice-level spells (Candlelight, Equilibirum and Oakflesh) for half magicka.
 * Alteration Dual casting: Can dual-cast an alteration spell for a more powerful version. (+10% effect compared to two individual castings, but +40% cost.)
 * Apprentice Alteration: Cast apprentice-level spells (Magelight and Stoneflesh) for half magicka.
 * Mage Armor: Three ranks. If not wearing armor, Stoneflesh (and similar spells) give 2x/2.5x/3x armor. Clothing, robes, hoods, rings, amulets, circlets and shields permit the bonus under this perk.
 * Magic Resistance: Three ranks. Reduces 10%/20%/30% of non-friendly spells. Note: Can combine with Agent of Mara (+15%), Lord Stone (+25%), and Breton racial bonus (+25%) to reach the cap of 85% with no gear.
 * Adept Alteration: Cast adept-level spells (Ash shell, Detect Life, Ironflesh, Telekinesis, Transmure and Waterbreathing) for half magicka
 * Stability: +50% duration
 * Expert Alteration: Cast expert-level spells (Ash rune, detect dead, Ebonyflesh, paralyze) for half magicka.
 * Atronach: 30% spell absorption. This blocks friendly spells as well as hostile ones.
 * Master Alteration: Cast master-level spells (Dragonhide and Mass Paralysis) for half magicka.

Training
Alteration spells are normally defensive, and thus gain in levels very slowly as they're generally cast once per encounter.

Skill training can be obtained from:
 * In exchange for money: Melaran at Solitude, Dravynea the Stoneweaver at Kynesgrove (south of Windhelm), and Tolfdir at College of Winterhold.
 * Dravynea gives 1 point if you give her frost salts.
 * Pantea Ateia (in the Bard's college) gives 1 point if you find her flute.
 * Skill books: Breathing Water, Bravil: Daughter of the Niben, Reality and Other Falsehoods, Sithis, The Lunar Lorkhan

The following options are available for self training:
 * Oakflesh and related spells only give experience near enemies. You can cast them near immobile enemies, near slaughterfish, or even cast novice illusion spell Fury on a chicken to qualify for XP.
 * Waterbreathing can be cast while standing in shallow water.
 * Telekinesis, although expensive, can raise alteration very quickly. With continuous use, it takes approximatly 17 minutes 20 seconds to raise from 15 to 100, which can be done with sufficient magic regeneration effects.
 * An exploit exists: If you reduce the cost of the spell to zero, and individual-cast two instances of telekinesis to pick up an an item, then fast travel while casting, this can level up Alteration to 100 within one load screen.
 * Detect Life, when used in a crowded area, can raise from 15 to 100 within 10 minutes. It works faster if there's more targets present.
 * Magelight and Candlelight provide a slow but easy stream of experience.
 * Transmute Mineral Ore can potentially train multiple skills at once (alteration, smithing, enchanting and speech)