Catastrophe Dragon Lord

Catastrophe Dragon Lord (カタストロフ・ドラゴンロード) is a Dragon Lord, one of the most powerful dragons in the New World.

Background
It seems that Catastrophe Dragon Lord was already dead as "Thousand Leagues Astrologer" of the Slane Theocracy predicted its revival.

The Undead King Arc
When Catastrophe Dragon Lord was predicted to revive, the Slane Theocracy readied the Black Scripture, one of the Six Scriptures, to deal with the situation.

The Bloody Valkyrie Arc
The Black Scripture had already reached the Great Forest of Tob along with Lady Kaire searching for the Dragon Lord to subjugate it using Downfall of Castle and Country. Apparently, when Ainz Ooal Gown's countered the Theocracy's divination spell watching Nigun Grid Luin, the Theocracy took it to be a sign of the Dragon Lord and were sent to the area near E-Rantel. They were forced to abandon their mission after they were attacked by Shalltear Bloodfallen.

The Lizard Man Heroes Arc
Zesshi Zetsumei inquires Captain of the Black Scripture about what happened to their group's mission on subjugating Catastrophe Dragon Lord. She begins to wonder whether Thousand Leagues Astrologer's prediction about its revival was false. However, the Captain dismissed her notion, informing her it was a powerful undead they encounter and not Catastrophe Dragon Lord.

The Ruler of Conspiracy Arc
According to the Cardinals, the threat of Catastrophe Dragon Lord is still at large. With most of the Theocracy's forces occupied and indisposed, the Cardinals hope to resolve the situation by using Downfall of Castle and Country on the said Dragon Lord if it does appear. They were hoping to use it as a vanguard against the Sorcerer King.

Abilities and Powers
The Catastrophe Dragon Lord's power is unknown, but it should be noted that the Cardinals sent all thirteen members of the Black Scripture armed with a World Item to defeat the Dragon Lord, which speaks volumes of its power. The fact that the Cardinals are confident that Downfall of Castle and Country would work on him imply that he isn't a True Dragon Lord and thus, cannot use Wild Magic.

Trivia

 * Prior to Shalltear getting mind-controlled, Catastrophe Dragon Lord was supposed to be the main target of Downfall of Castle and Country.
 * While the Cardinals of the Slane Theocracy were hopeful of using Catastrophe Dragon Lord to defend their nation against the Sorcerer King, they are also a bit doubtful of it happening, since Thousand Leagues Astrologer's prediction has yet to come true and hence, can't carry out the plan.