On November 5, 2018, after skipping his junior year and a part of his senior year to play in Lithuania and his father's Junior Basketball Association (JBA), Ball joined SPIRE Institute, a prep school in Geneva, Ohio, for head coach Jermaine Jackson. SPIRE competed outside the jurisdiction of the Ohio High School Athletic Association (OHSAA), allowing Ball to play without concerns over his amateur status. A number of prominent high school teams canceled their match-ups with SPIRE because Ball's professional experience would threaten their eligibility under their state federations. He was ruled ineligible for the 2019 McDonald's All-American Boys Game due to his professional experience. In January 2019, his team was removed from the Hoophall Classic tournament after event organizers did not meet a $10,000 request from a Ball family associate in order for Ball to play. On March 9, Ball was named MVP of the Grind Session tournament after helping his team reach the championship game.