Head back to RuneScape gold the aviansie in the Eagle's Peak Mountain. They will tell you your own soul is at risk after helping Azzanadra. Describe to them the location of Jaldroacht Pyramid, and they will issue orders to the Desert Eagle underneath them. Next, you will be told that Azzanadra must be intending to use the Vault of Souls into ressurect Zaros. Its place is unknown, but it will be in a cursed place.
You're told the place is also underwater. Head to the Ancient Cavern, and try to start the Mithril Doors. You're thrown backward, and several spirits seem. Now, you must run. Proceed to the Oracle, and she will shriek when she discovers you went there. She'll inform you only a legend that wielded an elemental power, and has been the master of his mind and body, ever escaped from the vault of souls. Go back to the Ancient Cave and kill a Mithril Dragon.
He'll automatically drop some chewed bones. Burn them out on a pyre ship. When nothing happens, talk to Otto Godblessed relating to it. He will suggest a potion to assist. Make a rest potion from soul weed and snape grass. Use it on your pyre ship, light it, and also a spirit will appear and provide you a key. He'll state you must also wield elemental ability and control both mind and body. Proceed to the elemental workshop to the area that has the zapper chair and across from it's a locked door with all the body rune symbol on itOpen it with your key and search some shelves to the publication of this elemental spear.
Go upstairs and make an elemental spear using 2 primed mind bars. Go back to the body room, wield your new spear, and pull the lever in the middle. While battling, your stats will be boosted dramatically. You may sew only thoughts armor against the Homunculus. After the battle is finished, your mind armor will have turned into Elemental Balance Armor. This armor has gentle melee stats. The spear (or, even when you've progressed enough through barbarian training, hasta) has medium melee stats, and will auto cast spells too.
Return to the Historical Cavern and try to go through the Mithril Door. You will triumph. There'll be several Nightmare Terrors and old school runescape buy gold Nightmare Spikes (Nightmare Spike-level 62, ranged user, can turn off your prayer randomly) attacking you.