G.I. Joe: Renegades Episode 17 Castle Destro Episode Title:Castle Destro.Episode Description:Tracing the prototype Techno-Viper's signal following its defeat, the Joes end up in Scotland. While there, the Joes become trapped inside Destro’s castle during a recon mission investigating a Cobra weapon called the Bio-Dag, a missile that dispenses Bio-Vipers en-mass.