A spellbook of haste self allows you to learn the haste self spell. This spell gives you very fast speed temporarily, making it a potential substitute for speed boots or a potion of speed. At unskilled or basic, the haste effect lasts for 100–109 turns; at skilled or expert it lasts for 160–169 turns. Unlike a potion of speed it will not heal your wounded legs, but it will still exercise Dexterity when cast.