Memento mori

Memento mori [mɛmɛntô môry] is the name given to Tennebrae's Ultimatum. Its primary effect is instantly killing any living lifeforms within 2200 kilometers (top limit of radius. Caster can limit.). This includes, but is not limited to: Humans, animals, insects, microorganisms, viruses, plants.

Its original user was Tennebrae, who then taught this technique to Lord Mirai, while still a member of The Elementals

The secondary effect manifests on humanoid entities that were affected by the initial effect. Individuals "killed" by Memento mori are still alive, though they have no way of displaying that. Their bodies cannot move and all life signs cease, with the exception of brain activity.