List of Core Ritual Examples:
1: Betrayal Ritual. Someone the target trusts must -knowingly- give them the item that will destroy them in an act of betrayal. The ritual can then be completed and whoever is wearing it, or the next person to wear it, bursts into flame taking 10d10 fire damage (No save), make a Wisdom Save or be frightened, and then take continuing 1d6 fire damage until the fire is out or the article is removed. Once the wearer is dead, or the fire is out, the ritual ends.
2: Terror Ritual. Anyone in the area must make a Wisdom save after a long rest to avoid falling under the effects. Those afflicted have disadvantage to Insight and Perception checks and must make a Wisdom Save any time they're exposed to monsters, violence, or other highly stressful situations or become Frightened for 1 minute. Once the Frightened Condition ends, make an additional Wisdom save or become Stressed. This effect lasts for 10 years, but anyone who performs 3 Ritual Murders within that time, or 1 Ritual Sacrifice, can reset the duration. The Sacrifice can only be performed in the place the ritual was initially cast. The Ritual Murders can happen anywhere within the area of effect.
3: Avatar Ritual. The ritual master becomes directly empowered by their god, growing to Huge size. They gain a bonus to AC and may cast one Cleric cantrip, whether they hold the knowledge of it or not, every turn as a bonus action. Any enemy of their faith must make a Wisdom save or be frightened for 1 minute on seeing them. Forgoing the use of their Bonus Action or Movement the Avatar can focus their attention on a single entity to attempt to Smite it. Doing so forces a Constitution Save to avoid bursting into flames, rotting, or falling into Madness. The target takes 10d10 Fire, Necrotic, or Psychic damage and is stunned for 1 round. For the duration the Avatar takes on physical aspects of their deity and may fly for up to 1 total minute. This effect lasts for 3 hours or until the Avatar is slain. If any member of the Ritual is not a true believer the ritual fails, and the Ritual Master knows who caused it.
4: Binding of Power Ritual. Up to 12 characters who take part in this ritual become temporarily empowered after eating the heart of a Giant Animal. Each participant gains a +2 bonus to AC, Advantage to Strength, Constitution, and Wisdom saving throws, +1d4 to all Weapon Attack and Damage Rolls, and expands their critical range by 1. In addition, they recover 1 Exertion every round and become immune to the effects of Fatigue and Stress for the duration, but may still gain levels of Fatigue and Stress. This effect lasts so long as the members are working toward a joint goal or up to 3 hours. If someone abandons their allies, or moves 120ft or more from their nearest ally, they immediately lose all benefits and gain 2 levels of Fatigue and 2 levels of Stress. When this effect expires all members gain 2 Fatigue.
5: Army of Darkness Ritual. When you cast this ritual, 40 monstrous entities rise in your service. You may choose whether this army is made up of Aberrations, Outsiders, or Undead, and may choose the visual appearance of these monsters. So long as you remain within 150ft of these monsters you may issue a mental command as a bonus action to direct them toward a goal. You may only issue one mental command on each turn, though you can make the monsters work toward different goals in groups by issuing commands across multiple turns. These monsters share a stat block, but gain different abilities and penalties based on their type. These creatures last for 3 days at which time 75% of those remaining are destroyed or dragged back to where they belong. The remaining 25% become uncontrolled, though if they had a specific goal before the end of the spell they will try to fulfill it before becoming free-willed.
6: Natural Disaster Ritual. Straight up summon a Tsunami, Earthquake, Hurricane, Volcano, or Wildfire to strike the area. Any exposed characters take 8d6 damage, as do buildings in the area of effect, with a Con, Dex, or Strength save to halve the damage (Narrator chooses save and damage type based on the disaster involved). Every round for 1 minute, the disaster continues and the damage and saving throws apply. After the effect ends, the area remains afflicted by the disaster's echoes. If there's a volcano it routinely blankets the area in ash and smoke. If there was a Tsunami, flooding becomes common. Earthquakes have continued rumblings. Hurricane-struck areas are always treated as having weather 1 step worse than they otherwise would.
7: Bind Horror Ritual. A number of participants with total hit dice equal to double the HD of the target Creature (Which must be an Outsider, Fey, Aberration, Undead, or Monstrosity) attempt to Bind it. Doing so traps it for 1 year and 1 day if it fails a Wisdom saving throw. Increasing the number of hit dice involved in the ritual, such as using 3 times as many hit dice, increases the duration by a factor of 10. Sacrificing a humanoid with 1/2 of the hit dice of the creature as part of the ritual also increases the duration by a factor of 10. This binding can be maintained by performing the ritual again during it's duration, by focusing on the container, location, or idea that is containing the Target. Extending the duration does not allow a Saving Throw. The maximum initial duration of the effect is 1,000 years. Subsequent Bindings may only add a maximum of 200 years to the current duration of the Binding.
8: Raise Building Ritual. Used extensively by Ancais, this ritual draws forth a fully shaped temple, fortress, castle, or other building from the bowels of the earth. References the Stronghold Rules of LevelUp and requires a Humanoid Sacrifice for each Space within the stronghold. The stronghold has an additional Hardness to all surfaces equal to the HD of the sacrifice used for a given space. If a 2HD slave is sacrificed to form the Kitchen, for example, the walls of the kitchen, as well as floor and ceiling, increase in hardness by 2. If 12 slaves with 1HD each are sacrificed to form the Curtain Wall, it gains 12 additional hardness.
9: Ritual of Censure. A curse placed upon the target causes them to lose access to Spell Slots above 3rd level and Martial Techniques which require 2 or more Exertion to use. Lasts for 24 hours and is generally used as part of Trials or Tests for the target, who must be present during the casting of the ritual itself. With additional components and sacrifices, the duration can be extended massively to contain or control powerful individuals who were not willingly Censured. The maximum spellcasting level can also be reduced as low as 1.
10: Disconnecting Ritual. This ritual is designed to directly counter other Rituals as well as to break a connection between a creature and it's power source. When cast upon the Ritual Master of an Army of Darkness it immediately frees all the monsters under the Ritual Master's control. When targeting an Avatar Ritual Master they remain Huge and retain the physical aspects of their deity, but lose access to the Smiting, AC bonus, and Cantrip-Bonus-Action casting abilities. When any member of a Binding of Power ritual is affected by this ritual, it is suppressed for the duration. The Disconnecting Ritual takes only 3 rounds to cast, but has a duration of only 3 rounds. At the end of which time the previous ritual returns to it's full power. When used on a creature which has access to Legendary Actions or Resistances, these are suppressed for the duration.