Annihilation event

Annihilation events are a phenomenon Xenoblade Chronicles 3. They are destructive events that damages 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 caused by a buildup of black fog in the area (which also jams the Iris). This is later used to create the Annihilator, a device that weaponizes black fog to trigger annihilation events at a distance.

While black fog is the predictor and cause of an annihilation event, there is no advance warning when one finally happens. A flash of light envelops a spherical area for a short time, followed by everything in said area vanishing without a trace. Anything on the edge of the effect is cleanly cut; anything above it may end up floating in midair instead of falling into the vacated space. Thus, within the space of a few seconds, a perfectly round hole appears in the landscape.

Story
The first annihilation event seen 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 occur frequently in Eagus Wilderness. When the party goes swimming at Lake Rezzento, a suspiciously round body of water, Taion warns Noah that annihilation events occur often in the wilderness.

N later does a test fire with the Annihilator weapon embedded at Keves Castle, destroying a portion of a mountain near the Urayan Mountains. The aftershocks is felt to at least Maktha Wildwood, the party's current location.

After P and O were defeated, they stayed in their Interlinked form for long, and consequentially, black fog began to build up around them. Fortunately, Noah and Mio manages to destroy the cliff where they're standing on, dropping them into the Great Sea, allowing the annihilation event to go off in a safe distance, taking P and O with it.