From TMW: rEvolt
The Hurnscald Bookshelf stands in Hurnscald, at the second floor of the Airlia's house. If you feel curious, you will maybe discover in it a strange manuscript signed by Potaffe about transmutation. Read it conscienciously, no doubt that you will increase your Magic knowledges. However, you must have the necessary Transmutation Magic Skill level to understand the manuscript's contents.
Spell taught by the Hurnscald Bookshelf:
You can find the script here.