Editing Magic in Harry Potter (section)

===Priori incantatem===
Priori incantatem is a spell-like effect used to reveal the spells cast by a [[Magical objects in Harry Potter|wand]]. The spells emerge from the wand as ghost-like replicas in reverse order, with the latest spell cast emerging first. Forcing two wands that share the source of their cores to battle can unintentionally cause a potent form of priori incantatem. The loser's wand will regurgitate shadows of spells that it has cast, in reverse chronological order. This side effect occurs during the duel between Harry and Voldemort at the end of ''Goblet of Fire''. Their simultaneous, contrary spells trigger the threads, and as Voldemort loses the battle of wills, his wand regurgitates, in reverse order, echoes of the people his wand had most recently murdered.