If you have any ideas for more spells, or a quest for this spellbook, please add a note on the discussion page. The Arcanus Mysterium (also called Arcane Spellbook) is a spellbook which is unlocked after a quest. This spellbook is famous for being the only spellbook which requires no elemental runes. Every spell costs at least one Arcane rune. It is often used in slayer or in Boss kills which do not use magic, as they can use the Arcane Form spell to protect themselves against the attacks and double their magic.