Alteration Ritual Spell


 * Prerequisites: 90 in Alteration skill
 * Quest Giver: Tolfdir
 * Reward: Dragonhide Spell Book, and you can purchase Master level Alteration spells from Tolfdir

Walkthrough
Once the player reaches an Alteration level of 90 and talks to Tolfdir, there is an option regarding learning more about Alteration magic. Select it, and Tolfdir will mention that he may be able to help if provided with Dragon Heartscales. However, the only weapon able to procure heart scales from a dragon is Kavohzein's Fang, prompting Tolfdir to ask the player to retrieve the Fang.
 * Video Walkthrough - Guide to: Master Level Alteration Spells & "Alteration Ritual Spell" quest (youtube)

Finding the Fang
Due to Skyrim's radiant quest system, there are several locations in which the Fang may spawn. Volskygge, Ragnvald, and High Gate Ruins are the most likely locations, but others may be possible. To find the Fang, simply travel to the location that the quest marker points to, and fight your way through any enemies that may hinder your progress.

Retrieving the Heartscales
Once the player has obtained Kavohzein's Fang, you must equip it in your right hand (doesn't work in left hand), then examine a dragon's corpse, whether recently slain or previously killed doesn't matter, will eventually yield Dragon Heartscales.

Finishing Up
Bring the Heartscales back to Tolfdir and he will reward your efforts with the Spell Book, which allows the user to ignore 80% of all physical damage for 30 seconds.

Glitches
Initiating the quest while Tolfdir is still standing outside Saarthal will cause the game to regard this as an ordinary quest, rather than as one related to the College of Winterhold. It will show up in the quest list with the default quest heading, and won't count toward the number of College quests completed on the info screen.