Damage. It is at the heart of rules for Dungeons & Dragons. Hit points are God and I've been exploring how to make them more versatile.
This is an excerpt from my forthcoming monograph, The Harrowed that expands on the variant rules for corruption, sanity and lingering injuries in Chapter 9 of the Dungeon Master's Guide.
In this low-fantasy variant arcane magic is not meant for mortals. Its use imperils the soul and corrupts the body.
Once per turn, the DM can have a a player roll a d20 immediately after their character casts a 1st-9th level sorcerer, warlock or wizard spell. This does not include cantrips.
On a roll of 1 their character takes necrotic damage. The damage taken is determined by the level of the spell slot used to cast the spell. See the table below. This may also result in a lingering necrotic injury (see below).
|Spell Slot Level||Necrotic Damage|
Variant: Lingering Necrotic Injuries
This variant gives an additional table for lingering injuries for necrotic damage. Continue to roll on the old Lingering Injuries table for non-necrotic damage.
|1||Corrupted Essence. Necrotic energies corrupt your blood, turning your veins black, white or green. Every time you take a long rest you must make a DC 13 Constitution saving throw or you take 1d10 necrotic damage as the foul energies eat you from within. Magic such as a greater restoration spell can restore your blood.|
|2||Withered. The necrotic damage seeps into your body, either withering your flesh as though you were mummified or rotting. This permanently weakens you and your Strength and Constitution are reduced by 2 to a minimum of 1. Magical healing of 6th level or higher, such as heal and regenerate, restores your body.|
|3||Sunlight Sensitivity. Your become very pale and averse to sunlight. You have disadvantage on attack rolls and on Wisdom (Perception) checks that rely on sight when you, the target of your attack, or whatever you are trying to perceive is in direct sunlight. Magic such as the regenerate spell can remove your skin and this penalty.|
|4||Second Head. You grow a second head on your chest, back or shoulders that speaks with your voice, but despises you. It speaks aloud every secret thought you have and contradicts you at every turn. You automatically fail all Charisma (Deception or Persuasion) checks you make against anyone who can hear you and understand you. Magic such as the regenerate spell can remove your second head.|
|5-7||Third Eye. Necrotic energies warp your flesh, causing you to grow a monstrous third eye on your forehead, the palm of your hand or your chest. You can choose to open your third eye as a bonus action. Make a DC 13 Charisma saving throw. On a success you gain truesight out to a range of 60 feet. If you fail the saving throw you instead catch a glimpse of the things that linger beyond human ken and are frightened for 1 minute and cannot move. If you roll a 5 or less you also gain a lingering psychic injury from the Lingering Psychic Injuries table. Magic such as the regenerate spell can remove your third eye.|
|8-10||Withered arm or hand. An arm or hand withers so it is skeletal or blackens. You cannot wield heavy weapons and make all Strength ability checks with disadvantage when using your hands or arms. Magic such as the regenerate spell can restore the lost appendage.|
|11-13||Withered leg or foot. A leg or foot withers so it is skeletal or blackens. Your speed is reduced by 5 feet. You must make a DC 10 Dexterity saving throw after using the Dash action. If you fail the save, you fall prone. Magic such as the regenerate spell can restore the lost appendage.|
|14-16||Psychic Lash. The necrotic damage lashes past your defences, corrupting your mind. Roll on the Lingering Psychic Injuries table instead (see lingering psychic injuries).|
|17-20||Witch's Mark. The necrotic damage marks your body in some way that singles you out as corrupted and you may need to hide it. Roll on the Witch Marks table below. Magic such as a lesser restoration spell can remove the mark.|
|1||You grow a large, furry spot somewhere on your body.|
|2||Your eyes turn completely white, red or black.|
|3||Your nose smoothes flat and your nostrils become slits.|
|4||Your skin is as cold as ice to the touch.|