I’ve been thinking about hacking Symbaroum’s Corruption into 5e by introducing the following mechanic to my game. Let me know if you can think of a more simple way to have a similar effect.

Shadow Scarring

All players begin with a Shadow Threshold of 5.

Shadow Damage

Shadow Damage occurs when an adventurer is exposed to corrupted forces, places, and powers. You may recover Shadow Damage by performing complex rituals, burning ceremonial herbs, resting in sanctified places, or visiting blessed healers. Actions that give Shadow Damage:

• Using a tainted power or ritual: 1 Shadow Damage, or varies per power
• Using tainted artifacts: 1 Shadow Damage, or varies per artifact
• Damage from shadow-tainted foe: 1 Shadow Damage per blow, or varies per ability
• Tainted areas: 1 Shadow Damage per day, hour, or per exposure to source

Shadow Scarring

Shadow Scarring occurs when the character’s soul has been indelibly marked by their experiences. Shadow damage cannot be reduced below the total number of Shadow Scars. Shadow Scarring is suffered when:

• Binding an artifact to oneself to be able to use its powers: 1 Shadow Scar
• Learning a tainted power or ritual: 1 Shadow Scar
• A character’s Shadow Damage reaches the character’s Shadow Threshold: 1 Shadow Scar

Levels of Scarring

• Shadow Blighted
  • At Least 1 Shadow Scar
  • The corruption can be detected with the Witchsight ability and rituals like Holy Smoke. Temporary Corruption can be resolved with a short or long rest.
• Shadow Marked
  • Shadow Damage above Shadow Threshold
  • The adventurer develops a temporary shadow mark that is plainly visible without divination magic or ritual. If you have shadow scars equal to the shadow threshold, the mark becomes permanent.
• Shadow Possession
  • Shadow Damage is 2x Shadow Threshold
  • The adventurer loses all control of themselves, the shadows have taken over. This often manifests as an immediate possession of the adventurer by a shadow beast.

Example: After spending 3 nights in the dark heart of the woods, each character has taken 3 shadow damage. During the morning of the 4th day, the party finally stumbles upon the source of corruption. The harmful radiation of the artifact penetrates their armor, making them feel as if they are freezing, they all take 1 shadow damage immediately bringing them each to 4. The wizard is prepared for this, and throws a specially crafted cloth over the artifact. As soon as it is covered, the adventurers all breathe more easily and the woods around them seem to brighten.

Later, the party takes a short rest and the wizard spends some time meditating with the artifact. His meditations are filled with visions of snow and ice. (The GM does not tell the wizard any specific mechanics about the special abilities of the artifact, only flavor) The wizard decides to attune with the artifact, this gives him one Shadow Scar but does not give him additional shadow damage. 

In the next scene, a rival party of explorers stumbles upon the group. They demand that the artifact be handed over. The wizard exposes the artifact, which is no longer harmful to the group as it has been attuned. He unleashes the power of the artifact on the rival adventurers, despite not knowing what it will do. The GM forces all party members except for the wizard to make constitution saves against the arctic chill, likewise rolling saves for each of the rivals. Those who fail freeze solid (5d10 cold damage), half taken on save. The wizard does not take cold damage, but does take 1d4 shadow damage taking him over his Shadow Threshold. He takes another scar as a result of his Shadow Damage exceeding his Shadow Threshold, and his veins blacken and grow pronounced through his skin as he is now temporarily Shadow Marked. The GM then explains the rules of the artifact ability (all other targets within 60 ft of wizard take 5d10 cold damage, constitution save vs. DC 18 for half.)

The cleric has survived, and rifles through the rival parties gear for the ceremonial herbs that they stole from the group earlier. When he finds them, the group takes a short rest as the cleric cleanses the souls of each surviving party member. The wizard’s black veins fade back to normal after the ritual, but now that he has 2 shadow scars he cannot fully heal. Every party member now has 0 shadow damage, except for the wizard who still has 2 shadow damage.

 

Art cropped from an Eric He image