There are 6 possible spellbooks in the Realms of Quest I, for your character to cast spells with [provided that your character has reached the required level to be able to cast the spells].
I had previously tried to access these spellbooks without avail as my character must not have been able to view them due to being of not high enough spellcasting level. Believe it or not, this is the first time that I have cast spells from a spellbook other than the first book of spells. I noticed that dungeon level 6 seems to contain a portion of the dungeon which is inaccessible unless you cast a certain level 4 “pass wall” spell.
Book of Spells level 1
Book of Spells level 2
Book of Spells level 3
Book of Spells level 4
If you cast the level 2 Invisibility spell, your character will turn the color red for the duration that your character is invisible.
If you cast the 4th level spell “Pass Wall” your character will appear the color purple as seen in a few screen-shots above, where Orangehat is in battle with a demon.
Take NOTE: That in order to cast spells from “Book of Spells, level 2”, you will need to use 2 Spell Units;
…to cast spells from “Book of Spells level 3”, you will need to use 3 Spell Units;
…4 Spell Units are required to cast level 4 spells, and etc…onwards…