Relíquias e rituais por Sword and Sorcery . O capítulo III do livro é intitulado Ritual Magic e o capítulo IV é intitulado True Rituals. Um trecho:
Beyond the dusty books and the quick gestures and the sonorous words that convey the power of spellcasters, there exists another level, one that rewards an even deeper understanding of magic. Most magicians and priests remain content to wield the power that they initially learn to control. Some spellcasters explore the subtle changes that they can exercise through metamagic feats, learning the truth beyond the magical tapestry and drawing upon even more powerful effects.
Beyond even these initial explorations, there is ritual magic.
Ritual magic can be broken down into three aspects: augmented ritual casting, combined ritual casting, and true rituals. Ritual magic is available to both divine and arcane casters within the scope of their training. The use of augmented and combined ritual casting is referred to as "ritual casting" of a spell, as these two types of ritual magic are used to augment a caster's normal repertoire of spells. Clerics may therefore apply ritual casting to the converted spontaneous casting of cure or inflict spells.
True rituals are entirely new "spells" that must be learned or researched individually in order for their power to be harnessed. Due to the exacting nature of preparing true rituals, they are only available to clerics, druids and wizards.
Since all ritualistic magic involves longer casting times and is much flashier in respects to casting techniques, opponents get a +4 bonus to all Spot and Listen checks against the caster(s) during the casting of any type of ritual.