Demonic Curses are Born from the Hatred-Fueled Ambition of Gods Turned Demons

When a god is fatally wounded and possessed with Ambition, corruption will darken its blood into worms and it will curse all things that touch it. Trees, flowers, stones, flesh--all rot, all are twisted.

See the demon's touch festering on his arm

Pick up a d8. This is your CURSE DIE. Then, roll for your curse and consult the table below. Whenever you make use of your curse, roll your Curse Die. On an 8, reduce you maximum hit points by 1. Next time you roll your Curse Die, you reduce your hit points by 2 on a 7-8. This trend continues until you reduce your maximum hit points by 8 whenever you use your curse. Yes, this will kill you--eventually.

There are TWO types of curses: Granted Curses & Demonic Curses. The former are the curses given to you by a witch or a god or something similar. The latter are  curses given to you when touched by something demonic or twisted. This blog post deals with the latter.

LIFTING YOUR CURSE

Frostbitten & Mutilated has an amazing d100 table for methods to break or lift a curse. If you don't want to use that, there are various Esoteries that can do the trick. Rare they are, and most times death itself is the only true cure.

Deny the curse to keep your life.

DEMONIC CURSES 

Using your curse forces you to do the thing it requires; for example, if the curse says you must attack something, then you MUST attack something to get the benefit of the curse. The curse, once invoked, has a lasting effect that ends at the end of the next round.

When choosing your curse, roll 1d20. That's your curse.

1. Hatred's Arm. When invoked, anger and fear overwhelm your character and you must attack or break something. Add additional damage dice equal to your character level when you roll damage next.
2. Move Beyond Death. When invoked, you hate all forms of happiness and must attempt to make something you see angry or emotionally hurt. At 0 hit points, you can stay conscious and active every turn you deal damage to something or someone.
3. Flesh For Skill. When invoked, you see all things as liars and can believe nothing anyone tells you. If you eat something's flesh or drink its blood, you gain 1 skill that it knows and can use it for 1 hour of time.
4. Attract Armies. When invoked, you believe yourself as the greatest leader, and ignore anything anyone else says. The next person whom you issue an order to must follow that order or suffer d6 damage. The order cannot force them to damage themselves.
5. Making the Heavens Move. When invoked, you know that you must do this thing and will do it, no matter what consequences are to be paid. When using Strength to push, move, or lift something, you do so automatically as long it isn't something ridiculous like a mountain.
6. Become Truer Than Their Mothers. When invoked, you lose all hostility for any creature that you can see. Up to 8 creatures that you can see become your followers/hirelings you as long as they weren't hostile already.
7. Wolf's Revenge. When invoked, choose an enemy that you hate beyond all else. You can make no other actions until you make an attack against that enemy, and you cannot attack it for 24 hours after invoking the curse. The attack is an automatic critical hit.
8. Smell Blood Like Honey. When invoked, everyone that can see you begins to bleed from both their nose and eyes. You know the secrets and goals of one bleeding creature that you can see.
9. Devour Murderer. Invokes only when you fall to 0 hit points. Every creature that sees your corpse must save vs Magic or die, giving you their hit points.
10. Worm Vomit. When invoked, you vomit worms made of thick ichor. These worms will crawl towards a person, place, or object that you're seeking for 2 rounds before melting.
11. Pain's Exhibitionism. Invokes only when you suffer damage, forcing you to damage yourself more. Any creature that sees you take damage suffers the same damage you are taking.
12. Remember Not the Taste of Tea. Invokes whenever you damage a creature. Said creature forgets who it was and what it was doing until the end of the next round.
13. Dominate Cowards. When invoked, you must show others that you are superior when compared to them, even if by force. Any creature that makes a moral check against you reduces their moral score by 6.
14. Memory's Dream. When invoked, you forget everything you know about one creature close to you that you can see. The next non-curse die you roll is treated as if you rolled the highest number possible.
15. Loyalty Misbegotten. When invoked, you realize loyalty is a lie and you must betray someone you have befriended or served. Any creature that sees this loses their action(s) on their next turn.
16. An Eye Trained on the Past. When invoked, you gain a hunger for another creature's eyes that must be fulfilled. When you consume an eye, you can see any 1 moment or image that the eye has seen.
17. Mutilations That Will Not Be Seen. When invoked, you must damage yourself so that others advert their eyes. Creatures that see you instantly forgot they saw you, and act as if you were never there.
18. Breaking That Will Break Sin. When invoked, you gain the urge to break or damage the next object you touch. Said object breaks and becomes utterly useless.
19. Words Eating Ambition like Snakes. When invoked, you must remind everyone you see that their goals and desires are pointless compared to yours. A creature you can see has their Ambition reduced to 0.
20. Actions Break Harmony like Rivers Do Mountains. When invoked, you must remind everyone that you can see that their peace is a treacherous lie. A creature you can see has their Harmony reduced to 0.

Breaking That Will Break Sin.