Prisoner of the Ring — Scott Sonneborn

On a distant planet, GREEN LANTERN battles an attack of formerly peaceful robots. He learns too late that the mechanical marauders are infected by an ultra-evil, ultra-advanced nano virus hungry for power. The wizard quickly invades the nearest form of high tech energy: GREEN LANTERNs ring. HAL JORDAN must shrink to microscopic size and enter the ring itself, or else his unlimited power will turn against the very galaxies he has sworn to protect!