Spell books are found throughout the dungeon, anyone can read them, but only players with high spell casting and wisdom can actually learn a spell. Cursed spell books will cause you to forget a spell, while blessed ones are easier to learn from.
Lower tier spells such as Light are easier to learn, requiring lower levels of the associated skills. Spell books are fairly time consuming to appraise, and get more and more difficult to appraise the higher the tier of the spell. Tiers aren't directly connected to any stat or skill in particular.
Below is a list of the spell tiers. For more details, see Spells.
|II||Fireball, Healing, Cure Ailment, Slow, Confuse, Sleep, Locking, Opening.|
|IV||Extra Healing, Lightning, Magic Mapping, Magic Missile, Identify, Remove Curse.|
|V||Levitation, Teleport, Invisible.|