Priori Incantatem

• Name: Priori Incantatem (also known as the Reverse Spell Effect)
• Type: Rare magical phenomenon
• Cause: Two wands with “brother cores” – cores taken from the same magical creature – are forced to duel each other.
• Effect: The connection between the brother wands prevents them from working properly against each other. The wand of the wizard who is being overpowered will be forced to regurgitate the spells it has performed, from most recent to oldest. These regurgitated spells manifest as “echoes” or “shadows” of their original effects or victims.
• Visual Manifestation: A thin thread of golden light connects the tips of the two dueling wands. This connection can expand into a golden, web-like, or dome-shaped cage of light trapping the two duelists.

The only known occurrence of Priori Incantatem in the series took place during the duel between Harry Potter and Lord Voldemort in the Little Hangleton graveyard. After Voldemort's return to power, he challenged Harry to a duel. Voldemort cast the Avada Kedavra curse, while Harry, acting on pure instinct, cast the Disarming Charm (Expelliarmus). Because both Harry's and Voldemort's wands contained a tail feather from the same phoenix, Fawkes, their spells connected in mid-air, initiating Priori Incantatem. A brilliant golden thread linked the two wands, and a dome of golden light erupted around Harry and Voldemort, sealing them off from the surrounding Death Eaters. Beads of light began to travel along the thread from Voldemort's wand toward Harry's. Encouraged by what he perceived as the sound of a phoenix song, Harry concentrated and forced the bead of light back along the thread to Voldemort's wand. This caused Voldemort's wand to “scream” and begin disgorging echoes of its most recent spells in reverse order:

1. An echo of the Cruciatus Curse Voldemort had just used on Harry.
2. The shadowy form of Cedric Diggory, whom Peter Pettigrew had murdered moments before with Voldemort's wand.
3. The shadow of Frank Bryce, the Muggle gardener Voldemort had murdered a year prior.
4. The shadow of Bertha Jorkins, a Ministry of Magic witch murdered by Voldemort.
5. The shadows of Lily Potter and James Potter, Harry's parents.

These echoes were not ghosts but tangible shadows of the past. They were not hostile to Harry; the forms of Voldemort's victims encouraged Harry and provided a diversion, swarming Voldemort and allowing Harry the precious seconds he needed to break the connection, grab Cedric Diggory's body, and escape to the Portkey. As explained later by Albus Dumbledore, this event revealed a critical magical protection: as long as Voldemort used his brother wand, he could not successfully duel Harry. This knowledge forced Voldemort to seek a different wand, first by borrowing Lucius Malfoy's and later by hunting the legendary Elder Wand.

Priori Incantatem should not be confused with the Prior Incantato spell.

• Priori Incantatem: A rare, spontaneous phenomenon that occurs between brother wands in a duel. It forces one wand to show a history of its previous spells.
• Prior Incantato: A specific spell that can be cast on any wand to reveal only its very last spell. Amos Diggory used this spell on Harry's wand after the appearance of the Dark Mark at the Quidditch World Cup to confirm it had cast Morsmordre.

The name is derived from Latin.

• Prior is Latin for “former,” “earlier,” or “previous.”
• Incantatem is a form of the Latin verb incantare (“to sing, to enchant, to cast a spell”) or the noun incantamentum (“spell, incantation”).

The combined phrase roughly translates to “previous spell” or “the former spell,” which accurately describes its function of revealing a wand's past enchantments.

In the film adaptation of *Harry Potter and the Goblet of Fire*, the visual effect of Priori Incantatem is depicted as a stream of red light from Voldemort's wand and a stream of blue or gold light from Harry's meeting to form a large, pulsating sphere of energy between them. The golden cage of light is also shown, and the echoes of Voldemort's victims emerge from the central energy sphere to aid Harry. (film)