Rituals
Rituals or incantations, depending on the source you read, are meant to give players new options to deal with problems outside of combat. Long casting times, spell components and high personal costs are trademarks of a ritual, which prevent the player from using them often.
Personally, I like rituals. They are like a cooking recipe: you gather the ingredients, prepare the food and start cooking. And the best part is you don’t need to be a spellcaster to be able to cast a ritual, you just need to have the appropriate skill. As a GM, this give the commoners and non-spellcasters of my worlds the ability to use spells in their daily lives. It gives evil NPC’s a chance to be preparing a ritual that will change the world, while the players try to interrupt it. It can even be turned into a quest, like making the players look for rare ingredients to perform a ritual to save a party member.
Rituals make adventuring easier and give NPC’s access to magical powers. Rituals should therefore be unique spells with a specific function or purpose and with that in mind I’ve started designing my own rituals. A ritual to disenchant or enchant magic items is a good example of a ritual that can make life a lot easier for a party. My veil gate and solar travel rituals give the players options to travel to other places that might be impossible for them to reach otherwise. Other rituals, like the art of war, hellfire assault and genesis are excellent rituals for villains to use in their evil schemes and in the hands of commoners some rituals can be used to protect themselves (Hidden Veil, Create Dwealmor) or as a means of trade (Enchant Magic Item).
Like the rituals in many other sources, my rituals come at a cost: often a ritual requires valuable items or even a part of the caster’s soul in the form of an xp cost. It might also leave the caster weakened or exhausted after finishing the ritual. Despite all that, the biggest cost is often paid when a ritual fails: rituals can suddenly have the opposite effect, give false information or can even lead to the death of the caster.