Bucket of water (can be obtained during the quest)
25 bones (can't be noted, but can be delivered in increments)
15 Combat level
Armour and some food
Fast travel to Varrock (Varrock teleport, Chronicle or (members only) Combat Bracelet to the Champions' Guild)
(Members only) Fast travel to the Wizards' Tower (Necklace of Passage, Amulet of Glory to Draynor Village, Amulet of the eye, or Fairy Rings to D-I-S)
To Start: Speak to Aris in the tent on the western side of Varrock Square.
Speak to Aris inside the tent west of Varrock Square. Pay her one coin to hear the tale of the demon Delrith, whom you must defeat. Ask about Wally's strategy against the demon and remember the answer. Aris will direct you to Sir Prysin.
Head north to Varrock Castle and find Sir Prysin on the ground floor southwest area. Tell him Aris sent you and request Silverlight, the weapon needed to kill Delrith. Prysin will explain that Silverlight is powerful and requires three keys to unlock. Unfortunately, he lost his key, while Captain Rovin and Wizard Traiborn hold the other two keys.
Acquiring one of the keys involves conversing with Captain Rovin, located on the palace's second floor, in the north-western section. Ascend the stairs within the north-west room twice to access him.
Engage in dialogue, explaining your need for the key to retrieve Silverlight, as a demon is poised to invade the city. Mention that Sir Prysin indicated he would entrust you with the key. Captain Rovin will express his allegiance to the King's commands and voice his reluctance to deviate from them. Upon this, inquire why Sir Prysin entrusted you with the key. He will reveal that the King's orders prevented him from misplacing it and subsequently hand over the key to you. However, he will impose a condition: that you ensure Sir Prysin does not succeed in slaying the demon.
Engage Traiborn in a conversation regarding certain keys in circulation. Locate him on the first floor of the Wizards' Tower, situated south of Draynor Village. To proceed, Traiborn requires 25 regular bones for a spell. For efficiency, ensure you possess all the bones before initiating the conversation. You can easily gather the bones by eliminating goblins south of the prison near Draynor Village. Present the bones to Traiborn, prompting him to conduct a ritual. Upon completing the ritual, he will provide you with his key.
Note for Ultimate Ironmen: If you're an Ultimate Ironman, you have the option to deliver the bones in stages, allowing you to avoid clearing your inventory all at once to fulfill this step.
Return to Varrock Palace.
Enter the kitchen situated in the north-eastern corner of the ground floor[UK]. If you lack a bucket of water, you can find an empty bucket upstairs and in the bedroom to the north-east. Acquire the bucket, descend the stairs, and employ it on the kitchen sink or a fountain to obtain a bucket of water. Then, proceed beyond the kitchen door and locate a drain near the wall north of the doorway. Apply your bucket of water to the drain – this step is essential for obtaining the key. The key will be flushed down the drain into the sewer. Depart from the palace's eastern side and spot a manhole positioned to the south of the palace walls. The Dungeon icon on the minimap indicates its location. Open the manhole and descend inside.
Return to Sir Prysin in Varrock with the three keys to receive Silverlight. Equip it and get necessary supplies.
If you forget the incantation, ask Aris in Varrock Square. Remember, it's unique to each player.
Go south of Varrock, east to the stone circle with dark wizards. A cutscene shows Delrith's summoning.
In the instance at the stone circle, defeat Delrith. Watch out for aggressive wizards. You might need to eliminate them before engaging Delrith.
Attack Delrith with Silverlight. His hitpoints weaken due to Silverlight's effect. When he's at 0 hitpoints, say the incantation. Get it wrong, he'll heal.
Non-melee pures with magic can use Silverlight and spells to finish him. You can also use debuffs to make him vulnerable to melee.
Remember the incantation, as Delrith might vanish if you take too long. If he vanishes during the banishing dialogue, continue until the quest ends.