A lot of this is ripped straight from Jeff Rients' Religion in Cinder
The Church of the Gold Dragon
"There are no good/metallic dragons in the World, only neutral and chaotic ones. The Church of the Gold Dragon is basically the Crystal Dragon Jesus trope taken to its illogical conclusion. I don't normally use this kind of faux medieval Christianity in my games, but I'm trying to step beyond my normal Howard-esque sword & sorcery roots to allow for pious knights and clerics and grailquests and all that sort of Arthurian stuff. But the Church isn't all gumdrops and lollipops. The faith supports the social classes of early feudalism, going so far as to divide its sacred texts into Copper, Brass, Silver, and Gold Codices. Only the Copper Codex is used in the presence of the peasantry. Nobles are given access to the revelations of the Brass Codex. The Silver Codex is reserved for clerics. Only the Patriarchs of the Church may read from the Codex of Gold."
- Jeff Rients
In my campaign this is the official religion of the Assyrian Empire. Churches are springing up in newly conquered lands. Missionaries are actively spreading the faith everywhere else. Metallic dragons are considered to be angelic beings who rarely if ever manifest in the world. Chromatic dragons are thought to be fallen angels who were cast out of Heaven. Priests of this faith work just like the generic cleric described in the 2nd edition Player's Handbook.
Cleric Alignments: Lawful Good (occasionally Neutral Good or Lawful Neutral)Weapons: only blunt
Spell Restriction: None
Special Abilities of the clergy: Turn Undead
"Your basic Greek/Norse/Kirby New Gods mash-up pantheon with a Mother Earth and a Father Sky and a sea god and all that standard stuff. Not necessarily opposed to the Church of the Gold Dragon, but open conflict between the two is certainly possible. The priests of the Twelve are losing ground in the long, slow competition for faithful followers, as the Church is better organized and the chaotic dudes (below) promise quicker results and more fun. Some priests of the Twelve are getting all apocalyptic on everyone's asses, claiming that falling away from the Old Faith will only hasten the end of the world."
- Jeff Rients
In my campaign these are the old Sumerian gods from beyond the stars, the Anunnaki. Most folk simply call this pantheon The Twelve, but priests of the faith would likely use the more traditional name The Seven, the Twelve, the Four, and the Thousand. The Four refer to the four gods of the fundamental forces, seen on the top row of the family tree. The Seven refers to "the seven gods who decree fate", these are the gods who sit in judgement over mankind and settle disputes among the gods; I marked these on the family tree with a little star. The Twelve refers to the major gods of the pantheon who aren't one of the four or seven already listed. The Thousand is a blanket term for all the other Anunnaki; demi-gods really, their powers are rather limited. On the family tree below Sharra, Ninshubur, and Ningishzida are the only members of the thousand who were listed.
Cleric Alignments: vary by deity
Spell Restrictions: vary by deity
Special Abilities of the clergy: vary by deity
Honestly I haven't bothered to determine the abilities of all these faiths yet. One of the PCs is a priest of the sun god Utu, so I can share those rules at least.
The Priests of Utu
Alignment: Neutral Good
Major Spheres: All, Divination, Guardian, Healing, Protection, Sun
Minor Spheres: Animal, Charm, Combat, Elemental
Restricted Spheres: Astral, Creation, Necromatic, Plant, Summoning, Weather
Turn Undead as if 2 levels higher
AC Bonus of 2 due to divine protection (sun glare, ect.)
Take the Hit: clerics of this faith are protectors and bodyguards who are known for throwing themselves into harm's way in order to protect the weak and the innocent.
The Frog God Cults
"Slaad worshippers. Chaos cultists in the tradition of Warhammer. Dudes in black robes wielding wavy-bladed daggers. Naked witches. Etc. In some areas a Frog God might be worshipped openly, but in many regions this faith has gone underground. The Frog Gods are not necessarily evil, but they are opposed to many of the institutions of Cinder society. And their propensity for human sacrifice puts them outside the law in many areas. Totally metal."
I decided to make these guys hybrid magic-user/cleric cultists. They use clerical spell progression, but their twisted gods grant them some magic-user spells along with the clerical ones; no spellbooks required. They can use both magic-user and clerical magic items, including scrolls. The healing spells cast by these guys are vampiric, meaning that you get to see the hp (blood and magical lifeforce juju) fly out from one person and into another. These vampiric heal spells have a range of 60 yards + 10 yards per level.
Weapons: as Magic-User
Armor: as Magic-User
Major Spheres: All, Divination, Charm, Any Necromancy (M-U or Cleric), Any Conjuration/Summoning (M-U or Cleric), Vampiric Healing
Minor - Elemental, Protection (reversed), Sun (reversed)
Detect Good 1/day
Self Mutamorphosis 1/body (roll d6 mutations on the mutation chart)
the vampiric healing stuff mentioned above
can cast spells beyond their level of ability by using multiple casters, long rituals, and sacrifices
Frog God Cultist Spell List
1st - Armor, *Bless, Chill Touch (MU), Combine, Command, *Create Water, *Detect Evil, Detect Magic, Detect Poison, Detect Snares and Pits, Detect Undead (MU), Endure Heat/Cold, Find Familiar (MU), Grease (MU), *Light, Locate Animal or Plants, Mount (MU), *Protection from Evil, *Purify Food and Drink, Sanctuary, *Remove Fear, Unseen Servant (MU), Vampiric Light Wounds
2nd - Aid, Augury, Barkskin, Chant, Charm Person or Mammal, *Detect Charm, Dust Devil, Enthrall, Find Traps, Fire Trap, Flame Blade, Glitterdust (MU), *Heat Metal, Hold Person, *Know Alignment, Melf's Acid Arrow (MU), Produce Flame, Resist Fire/Cold, Slow Poison, Speak with Animals, Spectral Hand (MU), Summon Swarm (MU), Withdraw
3rd - Animate Dead, *Continual Light, *Cure Blindness/Deafness, *Cure Disease, Dispel Magic, Feign Death, Flame Arrow (MU), Flame Walk, Hold Undead (MU), *Locate Object, Magical Vestment, Meld into Stone, Monster Summoning I (MU), Negative Plane Protection, Phantom Steed(MU), Prayer, Protection from Fire, Pyrotechnics, *Remove Curse, *Remove Paralysis, Sepia Snake Sigil (MU), Speak with Dead, Starshine, Stone Shape, Summon Insects, Vampiric Touch (MU), *Water Breathing, Water Walk
4th - Animal Summoning I, Call Woodland Being, *Cloak of Bravery, Contagion (MU), *Detect Lie, Divination, Enervation (MU), Evard's Black Tentacles (MU), Free Action, Imbue with Spell Ability, *Lower Water, Monster Summoning II (MU), *Neutralize Poison, Reflecting Pool, *Tongues, Vampiric Serious Wounds,
5th - Animal Summoning II, Animate Dead (MU), Atonement, Commune, Commune with Nature, Conjure Elemental (MU), *Dispel Evil, Insect Plague, Leomund's Secret Chest (MU), Magic Font, Magic Jar (MU), Monster Summoning III (MU), Mordenkainen's Faithful Hound (MU), Quest, *Raise Dead, Summon Shadow (MU), *True Seeing, Vampiric Critical Wounds, Wall of Fire
6th - Aerial Servant, Animal Summoning III, Animate Object, Conjure Animals, *Conjure Fire Elemental, Death Spell (MU), Ensnarement (MU), *Find the Path, *Heal, Invisible Stalker (MU), Monster Summoning IV (MU), Reincarnation (MU), Speak with Monsters, Stone Tell, Word of Recall
7th - Confusion, *Conjure Earth Elemental, Control Undead (MU), Creeping Doom, Drawmij's Instant Summons (MU), Exaction, Finger of Death (MU), Gate, *Holy Word, Limited Wish (MU), Monster Summoning V (MU), Mordenkainen's Magnificent Mansion (MU), Power Word Stun (MU), *Regenerate, Reincarnate, *Restoration, *Resurrection, *Succor, Symbol
Ritual Only (multiple cultists and sacrifices required)
Trap the Soul (8th)