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A Runemaster is a rather small Heartless that wears long, white robes with black and lilac highlights that cover its feet. It also wears a tall, cylindrical, black and grey hat with a white brim and what seem to be black gloves. Its collar is rather high and yellow. The only parts of the Heartless not covered by clothing are its spherical, blue head and yellow, glowing eyes. All Runemasters hold a book known as the Akashic Record+.
The Runemaster's name holds a similar meaning to that of the Bookmaster, and references magical runes.
Runemasters are unable to take damage from the front and will be blocked by the book, causing Sora's attack to be deflected. Since it is also immune to magic like the Bookmaster, the only way to defeat it is by attacking from behind. Trying to "chase its tail" can be a challenge because the Runemaster will try its best to keep its back away from Sora. Rapid attacks from Final Form makes the process much easier as it can rapidly attack the Runemaster from the front without the attacks being deflected. Reflect Magic is also a good way to defeat it, as the spray of light ignores protection.