The Harun-El, also known as the Rock of Yuda Kal and referred to as Black Kryptonite by Lena Luthor, is a mineral with a mutagenic effect and seemingly magical powers, originating from the planet Krypton. It can be used as a source of energy, healing, and power imbuement.
Harun-El was used on Krypton by the Children of Juru to imbue the Worldkillers with the dark magic of Yuda Kal. On their homeworld or in Argo City, it is harmless to Kryptonians but on Earth, the substance becomes toxic to Kryptonians and can be used to split a Kryptonian in two, such as when Lena used it to split Reign (evil) and Samantha Arias (good). When Kara used it to send herself, Reign, and Sam into the Dark Valley to defeat Reign without casualties, it split Kara in two, sending the other half to Kaznia unbeknownst to her.
Harun-El is also an incredible power source able to power the dome of Argo City as well as sustain an ecosystem and the artificial gravity on the asteroid that houses Argo. Argonians now have a recipe to make the substance from elements on Argo, courtesy of Lena who figured out how to make it.
Black Kryptonite also serves as a miracle cure all for any and every conceivable form of ailment/disease imaginable, as was proven true by Lena's thorough experimentation. But it also has the side effect of giving potentially fatalistic superhuman abilities onto the host recipient, powers which put an enormous amount of stress on an organisms major metabolic functions; e.i. cardiac malfeasance, blurred vision, debilitating migraines, neurocognative paralysis, nosebleed, etc.
Effects of which that can be negated by repetitious injections of Harun-El, if only temporarily as such a process briefly stabilizes its taker's. Not outright fixes them, in-so-far Lex is the only user who lacked such a limitation.
The Harun-El can be used to synthesize a chemical compound that would bestow a human being with extraordinary abilities.
- Strength augmentation: The Harun-El seems to enhance the user's strength to the point where a human can physically combat solar-powered Kryptonians.
- Regenerative healing: The Harun-El bestows its user with a regenerative healing factor. Upon being injecting with Lena Luthor's Harun-El drug, Lex Luthor and Bitsie Teschmacher were healed from cancer while James Olsen recovered from lethal wounds. When Lex used his Harun-El-empowered blood to give Red Daughter a blood transfusion, it managed to strengthen her weakened immune system and stabilize her physiology.
- Sensory augmentation: Due to being injected with the Harun-El, James can "zoom in" on people or things at a distance and even hear better than a normal human.
- Flight/Levitation: A few individuals who took the Harun-El serum gained unsupported aviation.
- Speed augmentation: Harun-El vastly bolsters personal locomotion by incredible strides; Ben Lockwood used his rapid motion to dispatch a platoon of Eve Teschmacher's clones.
- Durability augmentation: Physical resilience is likewise bolstered by Harun-El, enabling the user to be impervious to fire and hard impact.
- Heat vision: The visual receptors of the individual host of Harun-El allow for the accumulation and redistribution of ambient infrared, microwave or X-radiation as focused thermal blasts from the eyes.
- Harun-El Extractor/Anti-Serum: Lena created a serum that can extract the Harun-El from a user's system.
Behind the scenes
- The concept of Kryptonite that grants humans superhuman powers was previously featured in Smallville, where various Kryptonite-afflicted meta-humans were the near-exclusive antagonists of the early seasons. However, in Smallville, the mutations were caused by Green Kryptonite.
- Black Kryptonite was also introduced on Smallville first as a substance that was able to split both Clark Kent and Lex Luthor. They were split into two separate sides of themselves similar to how it works in the show as well.