RAUDSKINNA (THE BOOK OF POWER)
• As an action, you present and invoke the book of power. Each fiend that can see you within 30 feet of you must make a Wisdom saving throw. If the creature fails its saving throw, it is charmed by you for 1 minute or until it takes damage. While it is charmed by you, it is friendly to you and other creatures you designate.
• You gain cold, fire, necrotic, and radiant resistance.
• Any necromancy spell you cast deals an additional 3d6 on its damage roll.
"A legendary book about black magic, alleged to have been buried with its author, the Bishop Gottskálk grimmi Nikulásson of Holar."