The Verdimillious charm's only appearance in the original novels is during the Third Task of the Triwizard Tournament. Before the champions entered the Hedge Maze, Albus Dumbledore instructed them that if they got into trouble and wished to be rescued, they should send red sparks into the air from their wands. During the task, Harry Potter discovered Fleur Delacour being attacked by a bewitched Viktor Krum. To signal that a champion was in distress, Harry cast the Verdimillious charm:
The green sparks successfully alerted the tournament officials, and Harry Potter heard Hagrid's voice shortly after, confirming the signal had been seen. Although Dumbledore had specified red sparks, the green sparks produced by this spell served the intended purpose of a distress signal.
The difficulty of learning Verdimillious is unknown. As Harry Potter was able to cast it successfully under duress in his fourth year, it is likely not an overly complex piece of magic. There are no known counter-spells; as a signal charm, a direct counter is likely not applicable.
The incantation Verdimillious appears to be derived from Latin.
viridis, meaning “green”. This directly corresponds to the green sparks produced by the spell.mille (“thousand”) or the English word “million,” suggesting a large quantity or shower of sparks.The name can therefore be loosely interpreted as “a thousand greens” or “a million greens.”