Content warning: animal sacrifice (mentioned).
The purpose of ritual magic in game is to...
- emphasise the power and mystery of magic
- to provide additional flavour, and to generate other :
- create adventure opportunities (fetch quests for ingredients, research, casters etc.)
- Require a great deal of preparation.
- Have a fairly specific effect (whereas spells, in game, work more like generalised tools).
- Have a duration limited by natural cycles (night and day, lunar cycle, seasons etc.
In PARIAH, the closest thing to a D&D spell is an invocation: these require some sacrifice on the caster's part, and are less reliable. In contrast with "spells" rituals:
- Require no personal sacrifice aside from time (often animal sacrifices are required).
- Require components and specific timing.
- Have powerful and predictable effects.