Campaign: Dungeons of Drakkenheim
Researching the Spell: A character who can cast 9th level spells can research Sacrament of the Falling Fire. To complete the research, the caster must spend 18 days of downtime and 900 gp.
Special: This spell may only be cast in an area covered by the Deep Haze.

  You perform a holy ceremony involving up to 12 faithful and willing humanoid creatures that ends when each participating creature drives a delerium shard into their chest. Those creatures become sanctified (see below).

  When you finish casting this spell, a hostile Shadow appears and attacks each participant, as a manifestation of that character’s inner darkness. The GM may determine that a character who carries great anger, fear, or hate in their heart causes a Wraith to manifest instead.

Sanctified by the Falling Fire
The Sacrament of the Falling Fire is a new spell known only to Lucretia Mathias and Saint Gresha, who cast the spells each day, at dawn and dusk respectively, at the Chapel of Saint Gresha on the Crater’s Edge. A character who participates in the Sacrament of the Falling Fire gains the following traits, so long as they adhere to the tenets and faith of the Falling Fire:

• You gain advantage on saving throws against being charmed or frightened.
• You gain resistance to necrotic and radiant damage.
• You are immune to contamination.
• If you die, your soul enters the delerium fragment embedded into your chest. You can’t be raised from the dead while your soul is in the fragment.
• The embedded delerium fragment does not contaminate or otherwise harm a character who keeps their conviction.

(I have also created the DD: Sanctified by the Falling Fire feat to apply the above traits to characters who recieve the Sacrament.)

Loss of Faith
A character who violates or loses their faith in the Falling Fire loses the protections of sanctification and the beneficial traits above. Instead, their body is directly exposed to the delerium in their chest and they immediately gain one level of contamination. Until the fragment is removed or they atone for their sins, their hit point maximum is reduced by 10 (3d6) and they gain a level of delerium contamination each time they finish a long rest.

Sanctified Delerium
A delerium fragment filled with a sanctified soul glows with golden light. It becomes inert and immune to all damage except bludgeoning damage from magical weapons. Sanctified delerium possesses no other magical properties and is worthless for all arcane applications. A creature holding the fragment can telepathically communicate with the soul held within. If a sanctified fragment is destroyed, the soul inside is utterly annihilated, but the fragment can be used in a spell to return the dead soul within to life.

Removing the Fragment
The sacrament ritual fuses delerium to the body. The fragment can only be physically removed through great effort, requiring one hour of work and a DC 25 Medicine check. On a successful check, the fragment is removed but the sanctified character suffers 55 (10d10) damage. The fragment can be harmlessly removed from a willing creature using a Heal or Wish spell.