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.
After Ash Williams spoke the wrong incantation, Vampirella (Vampirella/Army of Darkness) was sent back to the Middle Ages and transformed into a powerful demonic, bat-like monster by the Necronomicon Ex-Mortis...
...a form she could later switch between on command after eating the page the curse was written on.
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.
Cursed by the Sisters, Hanzo (Kubo and the Two Strings) was transformed into...
...an anthropomorphic beetle, granting him the power of flight, six limbs and the ability to hold his breath for extended periods of time.
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.
Hector Barbossa (Pirates of the Caribbean) was cursed by The Cursed Aztec Gold, which transformed him and his entire crew into undead immortals,...
...preventing all of them from dying and making them virtually indestructible, while also causing physical limitations to their lives.
Jack Sparrow (Pirates of the Caribbean) gained the same curse from The Cursed Aztec Gold as Barbossa and his crew by secretly stealing one of the cursed coins.
Barbossa's pet monkey Jack (Pirates of the Carribbean) was also affected by the Cursed Gold.