[x] Armor up, then bust down the door. Save or subdue anyone as necessary from the explosion or shenaniganry which is afoot.
Uses less time than trying to be more quiet would be my justification, I suppose? The explosion could be something innocent, or could be a more mundane concern than mystical/criminal mumbo-jumbo that someone's trying to put out or get away from so a fast response might be best?
...Admittedly, I kind've just want to read about Shirou and Arturia doing a side-by-side application of heel to door that shoots it off it's hinges and makes for a collective 'What?' response from everyone inside.