Ten Archangels of the Sephira

Ten Archangels of the Sephira (セフィラーの十天使) are a group of angel bosses from YGGDRASIL.

Background
The Ten Archangels of the Sephira are among the World Enemies created by YGGDRASIL developers for players to later encounter and challenge it at some point during their journey in the game.

The Dark Warrior Arc
While there was a conversation going on between members of the Swords of Darkness, Ninya brought up the likelihood of their group facing a powerful race like dragons. However, her companions dismissed that scenario to be next to impossible as the chances of them encountering dragons were extremely low. Still, it caution Ainz to think about the World Enemies from YGGDRASIL who comprised more than just dragons alone, but also angels as well. Such angelic beings are said to be the Ten Archangels of the Sephira who are classified as World Enemies.

Strength
Similar to their angel variants, the Ten Archangels of the Sephira should also possessed the capacity to fly as well as using very powerful divine might to smite their foes.

While the Ten Archangels of the Sephira are immune to unenchanted attacks, the same could even be said with the rest of the World Items' abilities not affecting them at all. Since they are considered as World Enemies, the Ten Archangels of the Sephira is probably the closest candidate to being the most strongest angels known in YGGDRASIL.

Certain extremely high-level angels like the Ten Archangels of the Sephira can possibly use skills that may prevent the use of teleportation in their vicinity.

Trivia

 * The Ten Archangels of the Sephira are likely part of the Archangel race.
 * Sephira is an alternate name of Sefirot, which according to the Kabbalah are ten illuminations of God's Infinite Light.