This guide is suitable for current RuneScape and Old School.
Speak to Father Reek whom is just South of the Al Kharid Bank, he will tell you he needs to find you. Then you reply Thats Me! He will ask you if you have the Silver Light, then your character replys yes I used it to slay the Demon in Demon Slayer. He will explain to you that there is a Dark Wizard called Denath who is trying to summon a Demon called Agrith-Naar, Denath has took a band of Dark Wizards to the Ancient Temple Underneath the Ruins of Uzer to summon Agrith-Naar there. Then Father Reed tells you you must wait until Agrith-Naar is summond then kill Agrith-Naar once and for all. He tells you to go and meet his brother Badden who has been spying on Denath, who is waiting for you in Uzer and Father Reed will come ones he has finished with some business he needs to take care of.
Going to Badden
Go out of the Shanty Pass and go south-easternly until you get to the rug merchant, talk to him and say I want to travel to Uzer and he will fly you there for 200gp. Once there talk to Father Badden and tell him Father Reen sent me, you may talk to him any time to recieve any more information about Deneath and Agrith-Naar, ask him what do you want me to do. He will tell you you must be ready for when Agrith-Naar is summoned, so you must infiltrate the Denath's Dark Wizard Gang and take part in the Demonic Ritual. Then go downstairs and go and get Black Mushroom, then use it with the Pestle and Morta (Make sure you have a Vial in you Inventory) and then use the Black Mushroom Ink with the SilverLight so you get a SliverLight (Dyed Black). Then go towards the Double Doors which is the Furthest Doors North, then talk with Evil Dave whom is standing by the doors. He will ask you what do you want, tell him you want to join there group, he says you have to be evil, tell him I am evil, he will say you outfit looks evil (asuming you have 3 black items worn, and you have the black Silver Light). He will then take you to see Denath he will rant on about how Agrith-Naar will help everyone, then ask him what do I have to do, he will ask you to remember this incantation note this down. He then asks you to make yourself a Demonic Sigil.
Note: Everyone ones Incantation is Diiferent for everyone, so note your incarnation down.
Go back to the demons realm (underneath the ruins of Uzer) and talk to Mathew. Ask him why did Joesph Run away, he will tell you he read a book which frightened him and he ran away. Then Mathew tells you to go and find the book to know what Denath is really up too. To find the book go out the portal and up the stairs and talk to the Clay Golem and ask him what did he see last night, he will tell you he saw a Dark Wizard running and he looked very frightened then he ran out to the desert but ran back and hid the book in one of the broken kilns. If you go to the back of the main Ruin you will find a Kiln, look inside it and you will find the book Joseph had, you can read it if you want it isn't a must.
Go back to Mathew and show him the book, he will relise that he Agrith-Naar will not give them all there wishes just kill them but if he tells Denath he is not going through with the ritual he will kill him, then the ritual will start. Then you must say the correct Ritual, the one Denath told you before. After it is complete Denath goes through a portal and then Mathew realises that Denath was Agrith-Naar all along and you must get the three people that left back to complete the ritual again but this time to get Agrith-Naar back so you can kill him.
Go and Pick up Denath's sigil which is left at the portal, then go out the portal and pick up the Sigil that was droped by the Dark Wizard which died by the Ghost's, then go and talk to Evil Dave he will tell you Eric is dead because Agrith-Naar/Denath killed him, tell Evil Dave he needs to go and get back into the portal then Evil Dave will give you Eric's Sigil. You should now have 4 Demonic Sigil's. Then go to the North-West Corner and pick up the Strange Implement.
When you go upstairs be quick because there is a Sand Storm outside, and it will constantly hit you. Then Convince Father Badden and Father Reed to go through the portal to help you complete the Ritual and give them each a sigil, then tell the Clay Golem to help you, he wont so then use the strange Implement on him and then talk to him and he will take the Demonic Sigil, then he will help you.
Note: This is when to prepare for the fight with Agrith-Naar, bring food armour and a good weapon.
Go back through the Portal and talk to Mathew he will ask you if you are ready to slay Agrith-Naar, if you are then say yes. Then read the book Joseph had until you find the Incantation, it will be the one you was told before but backwards. Then get in the Position Denath was in before and read that Incatation. Agrith-Naar will appear and kill Mathew, you tell himit was you who betrayed him.
Note: If you say it wrong just step anywhere and you can do it again.
Agrith-Naar will start attacking you, make sure if you have it use Protect from Magic while you are fighting him. You can kill him with any wepon but the final blow has to be with the SilverLight. Once he is dead Un-Equip the SilverLight and it will turn into the DarkLight.
Congratulations! Quest Complete!
Guide Made by: Simon
Corrections submitted by: Simon, Jei, Power of Five