Annihilation event

Annihilation events also known as annihilation effects are a phenomenon in Xenoblade Chronicles 3. They are destructive blasts that damage the landscape of Aionios.

Description
Annihilation events are not well understood by the people of Aionios. They are treated as a natural event that can occur without warning in any place at any time, generally preceded by a buildup of black fog in the area (which also jams Iris communication). Black fog is later used as a component of the Annihilator, a device that weaponizes black fog to trigger annihilation events at a distance.

Annihilation events can also occur in a localized area if Moebius or Ouroboros stay Interlinked for too long.

Though an annihilation event is preceded by black fog, there is typically no advance warning before one suddenly occurs. A flash of light envelops a spherical area for a short time, followed by everything within the sphere vanishing completely. Anything on the edge of the effect is cleanly cut; matter above the effect may end up floating in midair instead of falling into the vacated space. Thus, within the space of a few seconds, a spherical emptiness appears in the landscape.

The mineral Enigmatter can be found in the aftermath of an annihilation event.

Story
The first annihilation event seen in Xenoblade Chronicles 3 is in the opening sequence where one destroys a middle section of the Urayan Mountains, followed by other smaller annihilation events in the surrounding areas.

Annihilation events appear to occur frequently in Eagus Wilderness. When the party goes swimming at Lake Rezzento, a body of water formed inside of a suspiciously spherical crater, Taion warns Noah that annihilation events occur often in the wilderness.

N later successfully tests the Annihilator weapon (which harnesses the power of the annihilation event) located at Keves Castle, destroying a portion of the Urayan Mountains. The aftershocks are felt to at least Maktha Wildwood, the party's current location.

Later, after P and O are bested by the party at Engardo Pass outside Maktha Wildwood, they persist in their Interlinked form for too long and, consequently, black fog begins to build up around them. Fortunately, Noah and Mio manage to destroy the cliff that P and O are standing on, dropping them towards the Great Sea, allowing the resulting annihilation event to go off at a safe distance, taking P and O with it.

While fighting against N at Agnus Castle, Sena and Lanz realize that they can destroy N by sacrificing themselves via annihilation event. While in their Ouroboros form, they grab onto him and launch themselves high into the air, preparing to run out their Interlink. However they are interrupted by X who severs their Interlink with her staff before they got the chance.

As it turns out, Agnus Castle also has an Annihilator. X uses this Annihilator to target the City and cause an annihilation event on Swordmarch.

Ultimately, at the Moebius battle at the Hall of the Serene, Joran refuses to cancel his Interlink with D, stepping off the ledge to fall into the void and sacrifice himself for the party to destroy D via annihilation event.

Lore

 * Origin was originally created to handle a universe-wide annihilation event, caused by the universes of Xenoblade Chronicles and Xenoblade Chronicles 2 colliding and annihilating into light.
 * Individual annihilation events are implied to be the result of imperfections in the stasis of Aionios, as it was created immediately before the universes composing Keves and Agnus contacted and mutually annihilated.
 * In particular, the annihilation effect from maintaining an Interlink for too long is implied to be a result of a Kevesi and Agnian having prolonged contact to such an extent that Aionios' stasis can no longer prevent the universes from locally contacting and annihilating.

Trivia

 * The annihilation effect is likely inspired by particle-antiparticle annihilation: In particle physics, each of the particles that compose matter has a corresponding 'antiparticle'. If a particle and its corresponding antiparticle contact, they annihilate, leaving vast amounts of energy (typically) in the form of light.