The Universal Energy core is a bit of engineering used to power the Kree's Psyche-Magnetron. It's nuclear charged with radiation frequencies racing up & down the various energy spectra, even accounting some radiations not known to mankind. This Power Unit could be made mobile and remote operatic through the right technological interface, capable of empowering it's handler as well as manifesting whatever it is they wish to have realized into the material world. These energy cores could also be used to power other forms of terrestrial tech from different worlds as well.
Eventually coming to be used as a crucial component during Operation: Galactic Storm, acting as both the battery and activator for the Shi'ar constructed Nega Bomb. The adversarial Kree soldier Yon-Rogg, long thought to've died by the disruptive explosion of the Magnetron device when Mar-Vell did final battle with him. Found himself instead to be empowered by it. Willing himself back to life through the device and gaining even greater power he could siphon off from the radically altered Kree/Human hybrid who was also affected by the PM machine, Carol Danvers. He would find great power from the remaining fragment of the device left over from his last battle as well as a secondary remaining fragment lodged within a third cranial lobe within the new Captain Marvel's brain.
After fusing with the remnant of a PM's power unit to become Magnitron, through a rather complex scheme involving hidden Kree tech deposits on and around the Earth. Yon-Roggs materialization abilities would be enhanced to the point of enabling him not only the ability to fabricate hoards of old enemies using the new Marvel's memories. But project a whole new Kree-Lar capital city from his own, with which to crush New York city and every living soul in it, as final revenge against Mar-Vell and Carol for wiping away his whole life many decades ago.