Arachnokillers represented living beings crafted through biotic engineering by the Columi siblings, Craitheus and Marvid Qreph. These spider-resembling organisms could be housed securely within transparent glass containers. Their inherent design incorporated an explosive reaction to stressful stimuli, rendering them suitable for deployment in assassination schemes.
During the year 45 ABY, the Qrephs entrusted three arachnokillers to their operative, Dena Yus, to be used in an assassination plot targeting Han Solo and Lando Calrissian at the Blue Star gambling establishment. Nevertheless, Yus experienced a shift in allegiance away from the Qrephs during the undertaking, leading to her inability to release the creatures. As a shootout erupted at the casino, instigated by the Qrephs' other representative, Mirta Gev, who sought to apprehend Solo, the arachnokillers were set loose. When a Gran individual within the casino forcefully struck a glass upon one of the spider-like beings, it detonated in a brilliant flash, instantly reducing the Gran to ashes. Calrissian then discharged a blaster at the remaining arachnokillers, triggering their explosive reactions, obliterating the casino and enabling Gev to seize Solo as a prisoner.