The user can create, shape, manipulate, and harness antithetical powers that are generally diametrically opposed to the user in terms of their nature. As said powers and forces are the opposite of the user's nature and being, harnessing them may come with a price.
After his cells were mutated by Vandal Savage to prevent him from absorbing yellow solar radiation, the New 52 Superman (DC Comics) resorted to using Kryptonite as an alternative power source, burning off his poisoned biophysical essence and allowing him to simulate his original powers...
...though it also affected his healthy cells which left him terminally ill and ultimately cost him his life.
Allen Walker (D.Gray-man), a confirmed Noah, wields the power of Innocence in battle.
Wrath (Fullmetal Alchemist 2003 series), a soulless, artificial being - homunculus - gains transmutation abilities thanks to Edward Elric's limbs.
Daolon Wong (Jackie Chan Adventures) uses Uncle's good chi to access and control the Three Monkeys' dark chi.
The angelic Jim Downing (Image Comics) wields demonic power through the Hellspawn symbiote K7-Leetha.
Despite initially lacking a heart, Roxas (Kingdom Hearts series), as the Nobody of a Keyblade wielder, can wield the Keyblade, which typically requires a Strong Heart.
As he was created with it spliced into his DNA, Superman X (Legion of Super-Heroes), despite being a Kryptonian, can produce Kryptonite in a variety of ways, such as energy beams...
...eye beams, and outright trapping opponents in Kryptonite structures.