Stupefy is the Stunning Spell, a charm used to render a target unconscious. It is also known as the Stupefying Charm or, more simply, the Stunner.
The Stupefy charm is highly valuable in dueling situations because it can quickly end a fight without causing lasting physical harm to the opponent. Beyond its use against living targets, the Stupefying Charm can also be used to halt the movement of objects. This versatility makes it a useful spell in many different scenarios.
