How to Find Sorcerer Rogier and Complete His Quest

First Meeting - Stormveil Castle: Reach the Rampart Tower Site of Grace. Head right along the rooftops and drop down through an open window to find Sorcerer Rogier. He will offer to sell Sorcery-based Ash of Wars. After defeating Godrick the Grafted, he will move to Roundtable Hold.

Ash of War: Carian Greatsword (2500 Runes)

Ash of War: Spinning Weapon (1000 Runes)

Second Meeting - Roundtable Hold: Rogier relocates to Roundtable Hold, near the balcony. To advance his quest, return to Stormveil Castle.

Defeat the Ulcerated Tree Spirit: From the Liftside Chamber Site of Grace, go west through a small door, down stairs, and over rooftops. Jump onto overhangs, defeat bats, and proceed south then east to a chamber with tree branches and water. Defeat the Ulcerated Tree Spirit.

Obtain the Clue: At the back of the cavern, examine the pool of blood in front of the remains of a giant creature.

Return to Rogier: Go back to Roundtable Hold and speak with Rogier. You can ask him about the creature's remains.

Speak with Fia: Have Fia hold you to discuss a secret. She will give you the Knifeprint Clue.

Black Knife Catacombs: Travel to the far northeast corner of Liurnia of the Lakes to find the Black Knife Catacombs.

Navigate the Catacombs: Progress through the catacombs until you reach guillotine blades. Ride the middle blade up. Defeat the necromancer, follow the path, and defeat another necromancer.

Find the Hidden Passage: Slash the wall at the far end to reveal a hidden passage. Summon D if available.

Defeat the Black Knife Assassin: Defeat the boss to obtain the Black Knifeprint.

Third Meeting - Roundtable Hold: Return to Roundtable Hold and give the Black Knifeprint to Rogier. Leave and return to speak with him again. He will mention Ranni.

Visit Fia: Before leaving Roundtable Hold, speak with Fia to receive a Sacrificial Twig.

Speak to Ranni: Travel to Caria Manor in northwest Liurnia. After defeating Loretta, proceed north to Three Sisters and find Ranni's Rise. Speak with Ranni the Witch about the Cursemark.

Return to Rogier: Go back to Rogier at Roundtable Hold. He will ask you to enter Ranni's service.

Final Meeting - Roundtable Hold: Return to Ranni and enter her service. Then, go back to Rogier. He will state he fears a long slumber. Refresh Roundtable Hold to find him asleep. He will pass away, leaving behind his Spellblade Set, Rogier’s Bell Bearing, and Rogier’s Letter.