Demon Slayer

Walkthrough
After being paid one coin, the gypsy will predict your future. She sees a vision of you fighting a mighty demon named Delrith, who was summoned during the Fifth Age and subsequently defeated by the hero Wally. She tells you that a cult of dark wizards is attempting to summon Delrith, and she sends you to talk to Sir Prysin for help. The gypsy will also give you an incantation. Write this down, as it is different for each player. Five different words make up the incantation and are randomly ordered. Because some are repeated, there are than 125 possible permutations. If you do forget the incantation, simply talk to the gypsy again at any time during the quest, and she'll remind you of it.

Go north to Varrock Castle and find Sir Prysin on the western side of the castle. Tell him that the gypsy sent you. Ask for Silverlight, the weapon needed to kill Delrith. He will say he has kept it hidden because of its power and needs three keys to open the case it is stored in.

First key
In the northwest corner of the castle is a set of stairs. Climb them twice to reach a room with Captain Rovin. Speak to him and tell him that a demon is going to invade the city, that you have to defeat it, and you need his Silverlight key. Select the option that says "Sir Prysin said you would give me the key" and then select the option that says "Then why did he give you the key?" After a small rant about Sir Prysin's clumsiness he will hand it to you.

Second key
The key is stuck down a drain behind the kitchen in the castle. Go get a bucket just upstairs the kitchen and fill it with water at any water source; the sink in the kitchen is close and convenient. Use the bucket of water on the drain and the key will be washed into the sewers. Enter the Varrock sewers using the manhole using the manhole located immediately east of the castle's keep. Follow the northwestern path until you get to a stream and search around there. Search for a rusty key on the ground; it will not appear on the minimap. Grab it.

Third key
Gather 25 sets of regular, unnoted bones. You can buy them on the Grand Exchange or kill almost any monster and take its bones. Head to the Wizards' Tower, located south of Draynor Village. On the second floor of the tower, talk to Wizard Traiborn about the key, and he will ask for 25 bones. Give them to him and he will perform a ritual, then he will give you the third key.

Banishing Delrith
Return to Varrock Castle and give the three keys to Sir Prisyn. He will give you Silverlight.

Now that you have Silverlight, it's time to fight Delrith. Head to the bank and withdraw any food, potions and armour you might wish to bring to the battle. Armour with good magic defence, such as leather armour, is good to bring. Make sure you're wielding Silverlight and head to the stone circle immediately southeast of Varrock's south entrance, where the dark wizards are.

A short cutscene will play in which three dark wizards and Denath summon Delrith, a tall, red and black demon. Denath will then notice you and run off.

When the cutscene ends, attack Delrith. He is combat level 27, which can be intimidating to lower-leveled players, but he is extremely weak for his combat level because he has not had enough time since his summoning to gain full access to his powers. He has 7 hitpoints and can hit a maximum of 3 damage, so most players should not have much trouble fighting him. By contrast, the level 20 dark wizard that fights alongside Delrith can hit up to 6 damage and both the level 20 and level 7 wizards can reduce your stats. Wearing armour that defends against magic will help against their spells.

Once you defeat Delrith, he will collapse onto the ground, and a prompt will appear. Choose the incantation that the gypsy gave you at the start of the quest and Delrith will be banished from this dimension. If you choose the wrong incantation, Delrith will be revived and the fight will resume until you defeat him again.

Reward

 * 3 Quest Points.
 * The weapon Silverlight. If you lose Silverlight, you can buy a new one from Sir Pyrsin for 500 gold coins. You can also sell it to the Wise Old Man in Draynor Village for 80 gold coins.
 * If you are a member, you can talk to Historian Minas at the Varrock Museum to receive 5 Kudos and there will be a Varrock Museum display of Silverlight.

Trivia

 * In RuneScape Classic, the battle with Delrith did not take place in an isolated battleground. Rather, Delrith had already been summoned and could be seen by anyone prior to starting Demon Slayer, but could not be fought until the proper point in the quest was reached. After the quest was completed, Delrith continued to walk around in the stone circle, but could not be attacked.
 * In the cutscene in which Wally banishes Delrith, Wally wields Silverlight as if it was a two-handed sword.
 * If you die at the Delrith battle, you will get a normal death and lose your items, yet the music playing in the background will still play.

Demon Slayer