An Engineered Success
From A KoL Wiki
After you kill the last liquid metal bugbear, the lights stop flashing and the siren goes off. Everything's quiet except for one lone bugbear drone that keeps going "intruder alert! Exterminate!" but eventually its battery winds down.
"Threat Or Murderbots Neutralized," the computer voice says. "Either Way, Restoring Power To Elevator." Woo!
Occurs at Engineering, after using 6 drone self-destruct chips against Liquid metal bugbears.