Mastery Book

Mastery Books are a type of consumable item in game. For nearly all classes, many of their 4th Job Skills can initially only be raised up to Level 10 with Skill Points. These Mastery Books allow you to increase the max trainable level of a skill from 10 to 20, and then from 20 to 30 (if the skill's max level allows for it to go that high). Note that some skills have an upper limit of Level 10 which cannot be increased with Mastery Books.

Earlier on in the game, Mastery Books were a lot more difficult to obtain, with Level 20 books having a 70% success rate and Level 30 books having a 50% success rate. Later on, Mystery Mastery Books were introduced, giving a random Mastery Book upon reveal. As of MapleStory: RED, Mastery Book 20 and 30 were introduced and sold via certain NPC shops, allowing for players to raise their skills' master levels for a small meso fee.

As of MapleStory: Destiny, all regions except ChinaMS have removed the need of Mastery Books. Mastery Books can be sold to NPCs for mesos or used for redeeming Spell Traces.

Picture and Name	Effects	Source
Mastery Book 20	Master Level of the chosen skill increased from 10 to 20 at a 100% rate
Mastery Book 30	Master Level of the chosen skill increased from 20 to 30 at a 100% rate
Mastery Box	Choose one: Obtain 500 Spell Traces Increase the Master Level of a chosen skill from 10 to 20 at a 100% rate Increase the Master Level of a chosen skill from 20 to 30 at a 100% rate