Cleric Nuance

Clerics are their deity's front lines, charged with combating evil (or good, or law, or chaos) and performing miracles in their deity's name. Every action they take reflects strongly on their deity and also on that deity's followers. Because of this, higher ranking members of the cleric's religion usually keep a careful eye on their subordinates, guiding and disciplining them as needed.
As clerics gain levels, their actions embody the will of their deity more and more. At least, they should. If this is not the case, the rogue cleric can expect to find other members of their religion on their doorstep, ready for a pointed conversation. Or worse.

Proficiencies

Weapons: Personal, Side.
Armors: Light, Medium.
Defensive Skills: Presence or Focus, Insight.
General Skills (pick 2 from each category):

• Religious Rites: Religion, Medicine, Planes, another knowledge specific to your religion
• Exploration: Climb, Swim, Drive, Perception
• Priestly Duties: Linguistics, Nobility, History, Performance

Partial Rest

When you take a Nap, you can recover expended spell slots by spending 1 HD per level of the slot.

Prayers

Instead of casting a spell, clerics pray to their deity, asking for divine intervention in the form of a miracle. Unlike wizards, who wrestle complex equations about time and space into their mind so they can fire them out like magic bullets later, clerics need only to ask their deity in good faith and the miracle will happen.

Preparing Prayers

Clerics gain their power from their faith in their deity. This magic does not bend the deity to the cleric's will, but instead takes the form of a reverent request, blessing, curse, etc., spoken in true faith. There are no magic words to prepare, so no preparation is necessary. A cleric can pray for any miracle they know of without need to prepare it first, and they "know of" all standard prayers (a.k.a. spells on the cleric spell list) that are less than or equal to half their level (rounded up).

"Casting" Prayers

You can "cast" or "pray" a prayer by making a Wisdom (Religion) Check (called a Prayer Check) with a DC equal to the level of prayer being cast + 12. No check is necessary for Cantrips.
If you are in combat, then the DC is 10 + prayer level instead, but each time you make a Prayer Check, the DC increases by 1 for each subsequent Prayer Check. The DC resets to Prayer Level + 10 when you are no longer in imminent danger, or when you take a Rest.

Prayer Check Results

Natural 20: your faith is exceptional. Any non-d20 dice the spell requires are maximized. If there are no non-d20 dice, then the GM can increase the effectiveness of the prayer in another way.
Success: your faith is sufficient. The prayer happens with no problems.
Failure: your faith was insufficient and doubts tug at the back of your mind. The prayer fails and you cannot cast that prayer again until you complete a Night's Sleep.
Natural 1: something has significantly shaken your faith. In addition to the regular penalty for failure, you have a Crisis of Faith (details below) and cannot cast any prayers for 1d4 rounds.

Crisis of Faith

When you confront that which is truly evil in the world and your deity remains silent, you may have a Crisis of Faith. These are triggered when you roll a natural 1 on a Prayer Check and can range from a minor setback to a life changing event. Of course, more experienced clerics have more resilient faith. At 5th level, you can change a single natural 1 on a Prayer Check to a natural 2 instead. You must complete a Long Rest to use this ability again. You gain an additional daily use of this ability at 15th level.

Minor Crisis

Most Crises of Faith are brief, lasting only for a few seconds. When you have a Crisis of Faith, you lose access to all of your divinely granted abilities for 1d4 turns. During this time, any ongoing effects from your divine abilities (such as a prayer you were concentrating on) are suppressed. They cease to function and do not require Concentration during this time, but the time still counts against their duration.
Once the last of these turns ends, you must attempt a Recovery Check by rolling a d20.

Recovery Check Results

Natural 20: your confidence in your deity returns in full force. Your divine powers return.
2-19: your confidence in your deity is restored. Your divine powers return.
Natural 1: your faith is truly shaken. You suffer a Major Crisis of Faith (details below).

Major Crisis

When you fail your Recovery Check, your faith is shaken to the core and you begin to question all that you believe. Your divine powers cease to function semi-permanently. In order to reestablish your link to your deity, you must reaffirm your faith through great deeds or religious rites that are specific to your faith.
Deeds of this nature could range from slaying a powerful creature who directly opposes your deity, to founding a new temple or shrine, to wandering in the wilderness in search of a divine revelation, to converting one or more people to your religion. The grandiosity of the task should be proportional on your level. A 3rd level cleric might only need to purify a restless graveyard, while a 20th level cleric might need to travel into the abyss to slay an ancient demon warlord.
You have one day per level to complete one of these tasks. Depending on your religion, a "day" might run from dawn to dawn, dawn to dusk, midnight to midnight, etc..
If you do not complete a sufficient task within this timeframe, your faith is shattered and you abandon your faith, losing all of your divine abilities but retaining abilities based solely on your skills, like proficiencies, languages, and possibly even some class abilities. Clerics who lose their faith are called Faithless.

The Faithless

Becoming Faithless effects different clerics in different ways. Some take the sudden loss in stride, transitioning to another class to continue their adventuring career. Others lose hope and wander away and become NPCs. Other clerics might turn against their old faith, or even turn to another faith (usually one that was opposed to their original faith). Yet others might make their way to their religion's center to seek answers and guidance from higher ranking members of their faith in the hopes that they may someday reacquire their divine connection. There are even stories of Faithless clerics who lose their minds or drop dead on the spot from the stress of the sudden severance to all that they hold dear.
Some Faithless clerics manage to regain their connection to their deity, and often become some of the strongest warriors that faith has ever seen. This is uncommon though, and many faiths take Faithlessness as a personal insult. Many religions will declare a Faithless cleric Anathema, forbidding them to contact their former friends.

Extra Hit Die Uses

You can use your Hit Dice to help reduce the DC of your spells. This functions differently depending on the situation, but you can never reduce the DC below its base of 8 + Spell Level.

Channel Divinity

You can spend 3 HD to Channel Divinity.

During Combat

During combat, whenever you cast a Prayer, you can expend a number of HD up to your Wisdom Bonus to reduce the Prayer Check DC by 1 for each HD spent in this way. You cannot reduce it below its base DC (8 + Spell Level). The HD you spend this way only effect the Prayer you are currently casting.

Outside Combat

You can use one HD to reduce the Climbing DC of your Prayer Checks by the amount rolled on the die spent. You cannot do this again until you complete a Meal.

During a Breather

When you complete a Breather, you can expend a number of HD up to your Wisdom Bonus to roll them. Your Climbing Prayer DC is reduced by the total of the HD you rolled. It cannot be reduced below its base in this way.

Religious Charges

In order to help guide the members of their religion on the right path, religions usually have a set of charges, rules, guidelines, or the like that followers are expected to obey. Clerics are no exception to this, and often have a much stricter set of charges than regular followers, or even priests. After all, they are the direct representatives of their deity in the world.
Acting contrary to one of your religion's charges can be a serious offence, resulting in discipline from the religion's clergy, or even causing a Crisis of Faith.
Below are example charges from religions common to Aedeva.

The Path of Stars

Not to be confused with The Council of Stars, followers of the Path of Stars serve Ava'tr, the All-Color Dragon.

1. Gather wealth, influence, and power.
2. Use your wealth, influence, and power to oppose tyranny.
3. Provide justice to those stationed beneath you.
4. Protect those stationed beneath you.
5. Destroy creatures of evil.

The Great Constellation

1. Gather what is yours.
2. Let none steal from your hoard.
3. Avenge those who serve you.
4. Protect your realm.
5. Destroy userpers.

The Fell

Followers of The Fell are servants of Ilgradnis.

1. Fight on behalf of those who cannot.
2. Destroy the evil others dare not resist.
3. Bring no harm to the innocent.
4. Embrace your fate.
5. Be ever ready to take up arms in my name.

Faith of the Burning Crown

Followers of the Faith of the Burning Crown serve Cir.

1. Do not practice arcane arts.
2. Do not practice the necromantic or illusory arts.
3. Bring to light that which is hidden in shadow.
4. Burn away that which is not in the light.

The Unstoppable Advance

Followers of the Unstoppable Advance serve Marn the Unstoppable.

1. Crush your enemies beneath your hooves.
2. Be the first into danger, and the last to leave.
3. Protect what is yours.
4. Bow only to the worthy, flee only my wrath.
5. Suffer not the arrogance of dwarven kind.