Smudgling was born in England in the mid-to-late 14th century. In 1379, she entered a duelling competition held in Dartmoor, in which wizards and witches from across Europe came to partake. According to contemporary reports, the contest (which was held at night, so as to avoid attracting the attention of Muggles) featured duelling of a level of skill that was almost unprecedented. 
Eventually, only four competitors remained, including Smudgling and three wizards. The judges of the competition — distinguished warlocks and wizards from several different countries — delivered rousing speeches to the contestants before the final three duels commenced, telling them, "Think big! Think bigger than you have ever thought before! Let us see this night magic on such a scale, that future generations will envy us for having witnessed such greatness!" 
The first semi-finalists then moved in front of the crowd. Keeping in mind the judges' advice to think big, the first wizard transformed himself into a bull and charged the second, who escaped death by quickly turning himself into a viper. The second wizard bit the first on the leg, sending him crashing to the ground in pain. 
Next, the second wizard faced the third, and brought a great storm cloud down from the sky, drenching his opponent in freezing-cold rain and forcing him to evade bolts of lightning. The third wizard then got the idea to call a powerful cyclone, which not only blew away the storm, but also the judges, most of the spectators and several trees. 
It took several hours for everyone to regroup. Frightened of what the third wizard might do for his encore, the judges attempted to talk Smudgling out of challenging him, telling her that it might be easier if they simply gave him the cup before anyone else got hurt, but she refused. 
Smudgling and the third wizard then went up against each other. On the count of three, the wizard began a long, complex incantation that would have caused a mountain to break out of the ground and fall upon Smudgling's head had he been given the opportunity to complete it. However, Smudgling beat him to the punch, quickly murmuring the incantation for the Disarming Charm and sending his wand flying out of his hand. She was awarded the title of "Supreme Dueller" and the Disarming Charm became one of the most useful spells in any dueller's repertoire.