Jon then met Paul O'Neill, who saw that Savatage had the potential to be a big act. 1987's "Hall of the Mountain King" was released to critical acclaim and is cited by many fans as being one of the band's best works. Two music videos were released and received rotation on MTV, for "24 Hours Ago" and the title track. On the resulting tour, Savatage supported Megadeth and Dio, but Jon had many conflicts with Dave Mustaine, who at the time was a serious substance abuser. After hanging out with Mustaine on a 24-hour basis, after the tour, Jon entered rehab.