Su'Kal

Discovery detects a life sign on the starship in the radioactive Verubin Nebula, and Saru suggests this could be the child of one of the starship's scientists. They jump there to investigate, and find a planet made primarily of dilithium inside the nebula. Saru, Burnham, and Culber transport to the planet, leaving Tilly in command of Discovery. On the planet, the away team find themselves inside a complex holographic simulation designed by the scientists to raise and protect the child. They find the child, Su'Kal, and discover that he was born with biology adapted to the planet and radioactive nebula, while the away team suffers from radiation poisoning. Su'Kal is not prepared to deal with reality outside the simulation, and when he becomes upset he creates an energy surge similar to the Burn. An Emerald Chain ship commanded by Osyraa arrives.

Summary from Wikipedia, CC BY-SA 4.0.