** When crafting a spellbook there is a chance it will get up to 3 magical properties. These properties can be Faster Casting, Faster Cast Recovery, Lower Mana Cost, Lower Reagent Cost, Mana Increase, Mana Regeneration, Spell Damage Increase, Intelligence Bonus and a few mage related Skills(Magery, Eval. Int., Meditation and Resist). All the properties can be up to 80% of the intensity range they normally spawn in.
The amount and intensity of the properties on a spellbook depends on your Magery skill. At 80 Magery you can get 1 property, at 90 Magery you can get 2 properties and at 100 Magery you can get 3 properties. At 110 and 120 Magery you can still only get 3 properties, but you will have a higher chance of getting them.
taken from this page
http://uo.stratics.com/content/skills/inscription.php