The 26-year-old enjoyed his best Championships in three in La Molina in 2011 as he claimed silver in the parallel giant slalom and bronze in the parallel slalom.
However he couldn't upgrade to a gold in the parallel giant slalom in Canada on Friday, finishing 12th as Benjamin Karl successfully defended his title.
Karl was also bidding to make it three in a row in the parallel slalom however Marguc had other ideas as he cruised to the big final.
Marguc saw off Andrey Sobolev, Kaspar Fluetsch and Andreas Prommegger before coming up against Justin Reiter in the battle for gold.
Reiter got the better of Marguc by 0.48seconds in the first run of the big final however the Slovenian turned the tide in run two to win by 0.60 for gold.
That dethroned Karl as the back-to-back world champion as he lost in the quarter-finals and placed sixth overall with Roland Fischnaller claiming bronze.
The Italian beat Prommegger with ease in the small final while in the ladies' parallel slalom Ekaterina Tudegesheva returned to winning ways.
She was making her 14th World Championship start in the parallel slalom with two podium finishes, including a win in the parallel giant slalom in 2007.
Tudegesheva also won bronze in the parallel slalom in 2009 and set up a third trip to the podium and second onto the top step on the final day in Stoneham.
The Russian comfortably progressed to the big final where she made light work of defeating reigning parallel slalom World Cup champion Patrizia Kummer.
Meanwhile Germany's Amelie Kober beat Hilde-Katrine Engeli for bronze once again having also met in the small final of the parallel giant slalom.