Dragons: Riders of Berk Season 7 Episode 3 - Something Rotten on Berserker Island Episode Title:Something Rotten on Berserker Island.Episode Description:The Riders are invited to Berserker Island where, to their shock and Snotlout's indignance, Dagur has made Gustav a Berserker apprentice. Just as they are about to celebrate his graduation, Savage and a faction of Berserkers start a revolt and imprison Dagur and the dragons. Snotlout and Gustav work together to free Dagur, but bit by bit under the gravity of the situation and Snotlout's pressure, Gustav's confidence wanes until he admits his cheating while under Dagur's tutelage. The riders and Berserker siblings still manage to defeat Savage, and Dagur, admitting Gustav's apprenticeship was faked to relieve Berk of him for a while, honors Snotlout with a Berserker trophy, though he still gets his name wrong.