Heron was selected as the SEC Men's Basketball Player of the Week for weeks 9 and 12 during his second season at Auburn. At the end of the regular season, Heron was selected to the AP All-SEC Second team. He averaged 16.4 points and 5.3 rebounds per game as a sophomore. On April 4, 2018, Heron declared for the 2018 NBA draft but did not hire an agent in order to maintain his amateur status. He announced that he was withdrawing from the draft but will transfer to be closer to his ailing mother in Connecticut. On May 31, Heron announced that he was transferring to St. John's and intended to seek a hardship waiver to play immediately. He was granted the waiver on October 13.