The player must first cast Regen on any or all of the party members and then open the disc tray before a unit takes action. The game does not run until the disc tray is closed, but the characters will continue to gain health. Effectively, one can cast Regen, take an attack, then open the disc tray to regain the health. Poison does not behave the same way as Regen, and will not work with this exploit. Regen is a constant rate over time, whereas Poison is chunks of damage at intervals.