Required item to use the Warlock Reading Spellbook skill 'Tetra Vortex'.
Fire, Water, Wind, Stone attribute magic, the magic of information about Tetra Vortex are written in the magical language.

[iRO Description]
An essential magic book for the Warlock Skill [Reading Spell Book]
Magic Power can be drawn out by reading the words written in this book.
It's written about the Four property magic, Tetra Vortex.