The power to be enhanced as a result of a malevolent force or negative mystical effect afflicting one's own body.
Mystical Torment Empowerment
User can increase their own physical and spiritual prowess via a negative supernatural affliction they have, this power usually activates when the user exhibits strong negative emotion or distress. As the user masters the power, the negative effects of the mystical affliction become less apparent as the victim's body becomes more assimilative to the curse. When the curse or affliction is removed from the user their powers will disappear until the curse is re-initiated.
Cursed Crew of the Black Pearl (Pirates of the Carribean: Curse of the Black Pearl)
Pintel & Ragetti
Jack the Monkey
Captain Jack Sparrow (Pirates of the Carribean: Curse of the Black Pearl)
Hanso/Beetle (Kubo and the Two Strings)
The Lava Monster (Samurai Jack)
Rumpelstiltskin (Once Upon a Time)
Zoso (Once Upon a Time)
Genie/Magic Mirror (Once Upon a Time)
Delphine LaLaurie (American Horror Story: Coven)
Jason Blood (DC Comics); via Etrigan Curse
Caine (DC/Vertigo Comics)
Ghost Rider (Marvel Comics)
Spawn (Image Comics)
Shikabane (Corpse Princess)
Tartarus Demons (Fairy Tail)
Cursed Mark Users (Naruto)
Saga (One Piece); via Shichiseiken
Renya (Code Geass)
The Prince (Prince of Persia)
Chakan (Chakan: The Forever Man)
Rachel (Ninja Gaiden)
Sonic Boom's Chicks (Skylanders)
Fright Rider (Skylanders)
Miroku (InuYasha) has been able to harness his Wind Tunnel curse as a potent weapon.
After being executed via the curse of Hom Dai, Imhotep (The Mummy) was granted numerous supernatural powers, most notably his immortality and power over the Plagues of Egypt.
After being trapped in the Earth by Aku, the "Lava Monster" (Samurai Jack) developed the power to manipulate the earth around him to his liking.
Sasuke Uchiha (Naruto) empowered by the Cursed Seal of Heaven.
Hector Barbossa (Pirates of the Caribbean) was cursed by The Cursed Aztec Gold that transformed him into an undead immortals...
... along with his crew are that prevents them from death and making them virtually indestructible, while causing physical limitations to life...
...the same with his pet monkey named Jack.
Jack Sparrow (Pirates of the Caribbean) gained the same curse from The Cursed Aztec Gold as Barbossa and his crew.
Jūgo (Naruto) is the source of the cursed seals.
Michael Myers (Halloween) is the bearer of the Curse of Thorn, granting him superhuman strength and immortality, but also filling him with an uncontrollable rage that drives him to kill his family members in the hopes that the rage will abate.