Shadowblight Notes

SHADOWBLIGHT
An affliction caused by the soul's exposure to intense necrotic energy, this will be tracked by a series of Necrotic Tokens that characters can accumulate over the course of their adventure.  The soul is strong, but it is delicate, and major enough imbalances will leave cracks that foul energies can seep in to fill.

Every time a character is revived through "normal" means such as the revive spell, they gain two Necrotic Tokens.  Resurrection under particularly strenuous circumstances, such as when the body is badly mutilated or damage so severe has been taken that the character's soul has been harmed, may incur additional Tokens.  Furthermore, contact with the essence of the Shadowfell or other sources of raw necrotic energy will also add Tokens.

Upon receiving enough Tokens, the character will advance to the next stage of Shadowblight.  Particularly severe encounters with necrotic energy, such as resurrection through a deal with the Ghost King or magic that specifically disrupts the user's soul such as a wight's life drain, will immediately advance them to a comparable position in the condition's next stage.  No mortal magic can reverse Shadowblight, though particularly powerful entities such as gods or Archfey can cure the condition.  The progression track is as follows:
Stage 0 (Normal): 0-3 Tokens
Stage 1 (Blighted): 4-6 Tokens
Stage 2 (Shadowed): 7-9 Tokens
Stage 3 (Damned): 10-12 Tokens
Stage 4 (Fallen): 13+ Tokens

Stage 1: Blighted characters experience no effects that are visible by mortal senses, but their soul is twisted, and this abnormality can be picked up on through magical means.  Spells that can detect undead, such as Detect Good and Evil and the Grave domain's Eyes of the Grave, will give faint readings in their vicinity, which can muddle their ability to detect actual undead while in the Blighted character's presence.  These readings aren't solid enough to specifically point out the Blighted character, but there will be something amiss in their presence.

Stage 2: Shadowed characters start to truly feel the influence of the Shadowfell, and this is when shadowblight truly becomes dangerous.  Aforementioned detection magic will more clearly point to the character's extraplanar energies, and various creatures such as celestials and fey will immediately recognize the darkness eating at their soul.  Shadowed characters gain a weakness to radiant damage and can only be healed by magical effects at half the normal effectiveness.  Characters will also experience a variety of physical symptoms, such as their irises slowly turning to black, their voice growing raspier, and their features blurring into the shadows--this grants them advantage to any Stealth checks made in total darkness.

Stage 3: Little of a Fallen character's soul remains by this point, and they struggle to maintain their foothold in the world of the living.  Their features start becoming distinctly inhuman, with pure black eyes, inky black blemishes spreading across their skin, and a voice more akin to a gurgling death rattle.  The shadows within them sear with pain when confronted by the energy of life--if they are ever targeted by any healing magic, they lose hit points equal to half the amount that would have been healed.  The character also gains the Sunlight Sensitivity trait, giving them disadvantage to any attack rolls and Perception checks made in sunlight.  A Fallen character also counts as undead for the purposes of any magical effects--they are susceptible to turning effects, can be warded by spells such as Hallow and Magic Circle, and may be immune to or interact differently with other spells or effects.  Finally, anything that may disrupt the necrotic part of their spirit (essentially prolonged and/or severe episodes of any symptoms of shadowblight) will threaten total collapse, meaning that the character is more susceptible to gaining Necrotic Tokens on an incidental basis.

Stage 4: Necrotic energy has completely taken over a Damned character's soul, leading to complete transformation into an undead shadow.  But such a creature is not meant to remain in the Material Plane, and it will immediately be banished to the Shadowfell just as any other spirit.  From there, it is doomed to forever roam the wretched landscapes of the plane of shadow...or, perhaps, doomed to pay the price of its bargains with the Ghost King.