Elven Slaves

Elven Slaves is the tentative name of a trio of elven women, who've been enslaved to Erya Uzruth within his Worker Group, Tenmu until his demise when he invaded the Great Tomb of Nazarick.

After their master's death, they now loyally serve the Guardians of the 6th Floor of Nazarick, Aura and Mare.

Background
The three elves were captured and enslaved by the Slane Theocracy. They were subsequently broken and later sold to Erya Uzruth. Under their new master, the elves served as the cruel man's personal harem and also his magical support team in Tenmu.

The Invaders of the Large Tomb Arc
The elves participated in the joint investigation of the mysterious tomb near Carne Village. Since Erya had to create a rapport with the other workers and encountering Momon, he was on his 'best' behavior, thus he refrained from bedding with the elves so as not to cause a scene. However, after the workers split up, he used the elven ranger as lure to find traps. The ranger managed to remain unharmed during the journey, reported to Erya about noise up ahead. They encountered Hamsuke, and the lizardmen. The elves stood at the sidelines providing buffs for the human. However Erya was clearly disadvantaged to the monster, to the point both his arms were sliced off. When he ordered them to use healing magic, they stood idly by, relishing in his suffering. After Hamsuke beheaded Erya, the elves began kicking the corpse, before collapsing to the ground.

The Ruler of Conspiracy Arc
Because they did not willingly trespass into the Nazarick, Ainz spared the elven slaves and allowed them to stay with Aura and Mare, hoping that interacting with other elves will help in the duo's mental development. They have become absolutely loyal to the two dark elves, even going as far as to dress them. While Aura and Mare find them to be a bit annoying, Ainz ordered them not to kill the former slaves.

Strength
Due to their conditioning, the elves despite possessing abilities of each a ranger, cleric and druid were at the mercy of Erya. They were mentally broken after being enslaved and were frequently abused and raped by the human. The elves only possessed the bare minimum of equipment, their clothes were made from the plainest fabrics available, without any defensive capabilities.

Trivia

 * In the Web Novel, the three elven slaves from Tenmu had their ears fully restored by Pestonya's magic and they became Aura's personal maids.
 * Note the pink-haired elf is the ranger, blue-haired elf is the druid, and the yellow-haired elf is the cleric.
 * Since the Elf Country has women fighting in the front lines during the war, these three could be hinted to be POWs captured by the Theocracy.
 * According to Maruyama, at some point in the future, he planned to write an unpublished erotic story between Mare and the three Elven Slaves. The conclusion will end with Ainz weeping from the loss.