Deep Darkness Dragon Lord

Deep Darkness Dragon Lord (ディープダークネス・ドラゴンロード) is a Dragon Lord, one of the most powerful dragons in the New World.

Background
Five hundred years ago, Deep Darkness Dragon Lord was a Dragon Lord who did not bother to participate in the war against the Eight Greed Kings. It is not certain whether this means the Dragon Lord was born after the battle or it simply ignored the war altogether. As a result, he was, fortunately, one of the few to have remained alive during that time period even after the war ended with the majority of his fellow Dragon Lord killed by the group of players.

Three hundred years ago, Deep Darkness Dragon Lord encountered a player from YGGDRASIL inside his cavern. There, he had a death match with the said player. In the end, the Dragon Lord came out victorious, slewing the player and later also claiming ownership over that victim's World Item for itself.

Two centuries ago, Deep Darkness Dragon Lord was part of a loosed alliance of six Dragon Lords. He joined this alliance in hopes of preparing himself for a fight against the next wave of players. Around this time, he was taught a powerful Wild Magic spell known as [Extinguish Soul] by his brethren, Elder Coffin Dragon Lord.

Currently, Deep Darkness Dragon Lord has apparently been dwelling in a large subterranean cave underground while living there ever since. According to Platinum Dragon Lord, he has no clues what Deep Darkness Dragon Lord is up to as it never bothers to leave the cave or adventured outside.

The Invaders of the Large Tomb Arc
When Rigrit suggests asking other surviving Dragon Lords for their assistance, Platinum Dragon Lord was doubtful that Deep Darkness Dragon Lord would cooperate with him in combating the new hostile existences from YGGDRASIL. Platinum Dragon Lord notes that Deep Darkness Dragon Lord has kept itself secluded from the outside world, having no slightest idea what his colleague is doing inside that cave of his.

Abilities and Powers
According to Maruyama, Deep Darkness Dragon Lord is deemed to be a powerful being in his own right as he was able to slay a player. In addition to that, his unique magic was said to be very strong while both its offense and defense is considered flawless. The said Dragon Lord would also have a slight advantage over defeating most of the Floor Guardians, except for Gargantua and Shalltear Bloodfallen, in a one to one battle.

Active

 * Extinguish Soul: A spell that made the Deep Darkness Dragon Lord more brutal than ever, it could kill any being other than those with the protection of the World Item.

Main Equipment

 * Unknown World Item: Deep Darkness Dragon Lord has an unknown World Item formerly belonging to the player it have defeated in battle. This said World Item is also classified as such to be one of the "Twenty," a one-time usable item.

Trivia

 * Out of all the Dragon Lords out there, Deep Darkness Dragon Lord seems to be the only one among his kins who has managed to kill a player.
 * The author Maruyama classified Shalltear as the Dragon Lord's "nemesis," suggesting that the vampire's power may likely be a hard counter to his magic.
 * In the D&D Beyond lore, there is a similar being called the "Deep Dragon" who also lived a subterranean lifestyle as Deep Darkness Dragon Lord. They are portrayed as being master manipulators whose aim was to triumph over other creatures through misguidance, mental domination, and deception.