Here are some early ideas for the way the ritual system might be set up along with some example rituals... Obviously I would have to tinker with the exact numbers for all of this. It would be easiest to adapt to a specific world where the desires of the pantheons are known. If anybody has some input about how this might be done, or knows any other systems that have been created for another game that are like this - let me know. It seems like somebody has probably done something like this before.
# of Ritual Power Slots Active at a Time: 1/level
Rituals of higher power may take up 2 or more slots. Extremely powerful ritual spells may take up 5 or more slots.
Once a ritual power is expended or elapsed and is no longer active a cleric character may immediately arm himself with a new ability if the proper ritual casting demands can be met.
Healing Touch: Cost = 1 slot, Duration = 1 week, Ritual = cleric washes hands in a preparation of exotic oils (GM determination) for 1 hour in a copper pot over a candle prepared from bee wax while chanting prayers for healing power from diety (pick appropriate God). Component cost approximately 10 gp. Effect/Power = while active the character can heal 1d6/lvl HP (max of 3d6) three times per day
Healing Hands: as healing touch but Cost = 2, The oils must be suffused with vital herbal spices increasing the component cost to 200gp/use. The Effect is the same but the the caster can heal 1d6/lvl HP (max 6d6) three times per day. Caster must be 5th level to use this effect.
Wracking Curse (non lawful or good alignments): cost = 2 ,Duration = Permanent until fetish destroyed or spell countered, Ritual = the caster of this spell must acquire a piece of the intended victim’s body. A single hair, nail clipping, or eye lash would be enough. They create a doll made of sticks bound with rope and cloth with the piece of the victims body sown into the doll. Once the doll is finished, the arms and legs are broken one at a time. They can be broken quickly or spread out - one broken at a time over years. Effect = the victim feels stabbing ghostly pains emanating from the broken doll limb. For each limb broken temporarily subtract -1DEX, -1CON, -1INT (for humans -4 to each of these stats is the highest level of this curse). Saving throws made that involve these aspects of the character (GM determination depending on gaming system used) should have a -1 / broken limb. The effect can be stopped immediately if the doll is destroyed by tearing it apart or burning it over a fire. Other clerics should be able to develop a counter blessing that will prevent this spell from working (DM determines the required components and costs to work this magic).