Before he was turned into a Vampire, Lord Rokta served as the queen's cryptkeeper in Sabek (GS-ADV2).

A powerful Vampire tasked to bring back the ashes of The Eldest from Ulos.

As it does so, a mist fills the sepulchre and slowly coalesces into an enormous bat-like figure in the center of the room. The creature introduces himself to you as Lord Yuvan Rokta (YOU-vahn ROCK-tah). - Outbreak in Undercity (RPA-ADV3) 

First encountered in the Ancient Sepulchre of Undercity.

Lord Yuvan holds himself above other beings with much shorter lifespans, but is always looking for worthy candidates to expand the spread of Vampires.

Despite the conflict between the Dragul and Nalos, Yuvan's goals were universal;

He wanted nothing more than to see a gate to his homeworld opened again, and to be reunited with the others of his kind who still live there. He was impressed by your will and mind, and he even bestowed his blessing on you, meant to bond you to him for eternity. - Gate of Brizoor Waal (RPA-ADVF)

As a Vampire, Lord Yuvan is able to hold people in place;

You find that your arms and legs will not obey you. Lord Rokta has you frozen in place.

The Vampire returns to mist and you regain control of your limbs.

Against your will, you find yourself retrieving the gray drawstring sack from your pack. - Outbreak in Undercity (RPA-ADV3)

He can also probe minds and visit memories;

You feel Lord Rokta’s presence in your mind, sifting through your memories like a pair of hands searching your head for lice. - Outbreak in Undercity (RPA-ADV3)

Lord Yuvan Rokta reveals that the Starlit Door has taken the ashes of The Eldest;

“The people who stole our treasures call themselves the Starlit Door,” the Vampire says to you with his mind. “Find them. Kill them. Bring me what is mine.” - Yuvan Rokta, Outbreak in Undercity (RPA-ADV3)

Recover them from the Library and return them to Yuvan:

• Attack him:
  • If you overpower him quickly, he will transform into a powerful bat:
    • Defeat him, and you vanquish the Vampire threat from Nalos.
    • Fall to him, and he will take the ashes and leave, vowing to remember your weakness.
  • If he overpowers you quickly, he takes the ashes and leaves vowing to remember your weakness.
  • If the tide of battle neither leads one way or the other, he will continue his onslaught:
    • Defeat him, and you vanquish the Vampire threat from Nalos.
    • Fall to him, and he will take the ashes and leave, vowing to remember your weakness.
• Await his estimation:
  • Win his approval, and he will grant you the gift of vampirism.
  • If you fall short of his needs for you, he will remember and consider your usefulness in the future.

If you sided with Yuvan Rokta in the Undercity, he will communicate with you telepathically, and you will be drawn to a shipwrecked vessel where he is trapped in a large wooden crate. He demands to be freed:

• Resist:
  • Succeed: You regain control of your own mind and return to your ship.
  • Fail: You cannot resist. You open the crate and are forced to fight Rokta.
    • Defeat him, and the Vampire perishes.
    • Fail to him, and you become infected.
• Obey his commands:
  • Receive Rokta's blessing (become infected).
  • Fight him.
    • Defeat him, and the Vampire perishes.
    • Fail to him, and you become infected.

If you sided against Rokta in the Undercity but failed, you will discover his shipwrecked vessel, and the captain of our ship will fall into a trance, ordering you to open a wooden crate.

• Open the crate. Rokta attacks.
  • Defeat him, and the Vampire perishes.
  • Fail to him, and you become infected.
• Help the captain snap out of it.
  • Succeed, and the captain captures Rokta.
  • Fail, and Rokta attacks.
    • Defeat him, and the Vampire perishes.
    • Fail to him, and you become infected.

Yuvan Rokta and the Ghost-Eater at his side fight Zalic and Gimlix in the emptiness of Moti, Plane of Death, at the final battle of Brizoor Waal:

• If you side with the Dragul, you will fight alongside him:
  • If you defeat the opposition and are favored by the Vampire, he will induct you ceremoniously. You claim the site, and find a black rune.
  • If you defeat the opposition and are disfavored by the Vampire, you will earn his consideration and claim the site, finding a black rune.
  • If you fall to the opposition, you stumble through a rift back to Elsifor's Tent at Brizoor Waal in defeat.

During the reign of Queen Gimnax, Yuvan was the royal cryptkeeper, who had a personal interest in extending his life, and not necessarily in service to the crown or Azema herself;

As you ask questions about the cryptkeeper, they voice their suspicions that he has conspired against the crown. They lead you to his private quarters and insist on showing you his notes and letters. Among them, you find a large stack of books on vampirism. It seems that the cryptkeeper’s fascination with the undead extends beyond Azema’s servants. - Servants of Azema (GS-ADV2)

“Yuvan Rokta, the cryptkeeper, holds a key identical to this one. I don’t know if he has ever used it to enter places forbidden to him, but I wouldn’t be surprised. There are rumors that he has consorted with elements disloyal to the crown.” - Temple priest, Servants of Azema (GS-ADV2)

In the catacombs below the city, Yuvan believes he is able to control the Undead Servants of Azema to his bidding;

• Assist him in attempting a necromantic spell to suppress the Servants.
  • Succeed, and quell the Undead uprising.
  • Fail, and black out as the horde overwhelms you.
• Take on the swarm by regular means.
  • Succeed, and cleanse the catacombs as Queen Gimnax assigned you to do.
  • Fail, and black out as the horde overwhelms you.
• Release the Servants of Azema on the populace, inciting Yuvan to act against you.
  • Succeed, and set loose the Undead in the name of the Dragul.
  • Fail, and you black out as the horde overwhelms you after Yuvan wrestles you to the ground.