Katerina was an expert on nuclear power during the cold war, working at chernobyl. She was working in the reactor core when the famous accident happened. She was missing, presumed dead. In the soviet machine, no tears were shed over the loss of one worker.
Some time later, when the zone was being closed off and excavated, she walked out of the ruins and destroyed the guard post there. She became something of a messiah for the people of the region, promising them a salvation from the hard regime. At first, she was noted for the fact that she had survived in the very center of the accident, a place where the radiation is intense enough to literally melt flesh from bones.
Over the next years, the area became noted for its fecundity and was recognized by the state.
After some years, an unrelated investigation discovered the cult worshipping her power, and an agent was sent to destroy her or capture her for government use. This was where she learned about her combat powers. She became a mercenary in various wars, but has since settled down and become a political advocate for clean nuclear power, but she will fight if it becomes necessary. She is a founding member of the Terra Protectors.
Unnatural fecundity - Katerina Emanates an aura that causes living things within several kilometers of her to grow faster and stronger than normal. It's not noticeable on a small scale, but it's there on a statistical view. However, there is also an increased chance of birth defects and cancer within this radius as cells grow out of control.
Plasma Generation - Katerina's left hand glows a sickly green color, and she can fire bolts of green plasma from it as ranged attacks. Her name, Green Hand comes both from this and the idea that she's got a green thumb a hundred times over.
Radiation Absorption - When she is exposed to radiation, either nuclear or just plain sunlight, she is healed and strengthened. At Chernobyl-like levels of radiation, she gains super human strength and speed as well as regenerative powers. As well, her plasma attacks become much stronger. Plain sunlight allows to never fall ill against common colds and the like. She can also forgo sleep or food for a while, using sunlight to replace some of what she would miss otherwise, but she can't do it indefinitely, maybe a week tops. It has however, slowed down her rate of aging, meaning that, despite being almost 80 years old, she doesn't look a day over 30