The Sanderson Sisters' Spellbook, also called Winifred Sanderson's Spellbook or Winnie Sanderson's Spellbook, is an evil magic book owned and used by the Sanderson Sisters (Winnie, Mary and Sarah) to create potions and cast spells.
This cursed spellbook was said to be given to Winifred "Winnie" Sandersonby the Devil himself. It is bound in human skin, it contains the recipes for her most powerful and evil spells. The book has a human eye on the front cover, and often sleeps, only waking to the sound of its mistress who dotes on and cherishes it, meaning the book is alive and, on some level, intelligent.
Among its contents is the Life Potion, an evil potion that allows the 3 witches to suck the life-force of the drinker to replenish their youth. Another is a number of spells that curses a vicim with immortality, transforms victims into cats, raise the dead, curses victims with boils and blisters, etc.
It's most important curse was that if in the event the witches were killed, that if a virgin lit the Black Flame Candle on Hallow's Eve (Halloween) during a full moon, the witches would return alive for one night unless they suck the life out of a child lest they turn to dust come sunrise.
The book is protected by magic and cannot be burned or destroyed. It is an unholy record of sorcery and nothing good can from it.
After the deaths of the Sanderson Sisters, the Book was last seen in the witches' cottage, opening its eye, and presumably remained there.