The Evil Shrine

Starting the quest
Talk to Golsharu in Zi Cochan. Ask him about the evil source coming from the shrine. He will tell you to go speak to the Wise Old Man in Draynor Village. This begins the quest. Talk to the Wise Old Man. He will tell you that the only way to get into the shrine is to find six mysterious medallions hidden all over RuneScape.

Sapphire medallion
Head to Entrana and speak to the Cave monk and tell him about the evil source coming from Desert Island. He will tell you that the sapphire medallion is guarded by the giant demon in Entrana Dungeon. He will give you a holy blade which requires 70 Attack to wield. He will also tell you that you need to defeat each of the greater demons in the dungeon once to make the giant demon appear. Head into the dungeon and use the holy blade to kill each of the greater demons. After killing all of them once, their spirits will combine to form a level 227 Giant demon! He can only be hurt by the holy blade, and can hit up to 220 with melee, so drink your prayer pots and use Protect from Melee to defeat him. He will drop the sapphire medallion.

Emerald medallion
Head to Ape Atoll (don't forget your greegree and monkeyspeak amulet) and speak to King Awowogei while in monkey form and tell him about the evil source. He will tell you that the emerald medallion can be found in the Ape Atoll Dungeon. Head to the Ape Atoll Dungeon and push away the boulders just south of Zooknock (this requires 80 Strength). Walk through the new passage and swing the vine over the pit of lava (requires 80 Agility). Continue through the maze swinging over the pits of lava and pushing away boulders until you reach the treasure chest. Search the chest for the emerald medallion.

Ruby medallion
Head to the south-westernmost point of the Kharazi Jungle. Use a rune pickaxe on the stone you find there to make a path come out from under the water. Follow the path until you reach the end of the path on a deserted island. Use your rune pickaxe on the stone you find there to make Washiwashi (level 318) come out of the water. Just remember that he can't be hurt by melee attacks. Once you defeat him, pick up the ruby medallion he drops.

Diamond medallion
Head to Al Kharid and talk to Osman about the evil source coming from Desert Island. You must have an ancient staff for this part. He will upgrade your staff to a Zaros staff if you give him 100,000 coins. Head to Jaldraocht Pyramid and use the Zaros staff on the altar to make a level 327 Sand spirit appear. It seems to be weak to air spells. Once you defeat it, it will drop the diamond medallion.

Dragonstone medallion
Head to Zanaris. Talk to Chaeldar and tell him about the evil source coming from Desert Island. Your slayer task will become the cosmic elemental and he will give you a cosmic staff and a cosmic blade. The cosmic blade requires 85 Slayer to wield. Enter the cosmic altar and use the cosmic staff on the altar, and Cosmic elemental (level 338) will appear. It can only be hurt by the cosmic blade. Once you defeat it, it will drop the dragonstone medallion.

Onyx medallion
Head to the TzHaar mine. Use a spade on the southernmost point of the mine. You will uncover a ladder. Go down the ladder. In this new location, you will be attacked by the TzZek-Ek-Ak. It is a level 350 monster which is represented by two TzHaar-like people. It is 2 monsters in one, as they share the same health meter. Their attack speed is twice the speed of a scimitar. Once you defeat it/them, it/they will drop the onyx medallion.

Desert Island Shrine
Once you have all six medallions, head to the westernmost point on Desert Island. Click on the door, and all six medallions will be placed on the door, opening it. Enter the shrine.

Make your way through the dungeon, avoiding the various monsters. There are also some agility obstacles. These include vines over blood, which if you fail, you will be warped to outside the dungeon and you will be poisoned, starting at 10 damage, and spiked crushers, which move back and forth. You have to avoid the spikes, or else you will die instantly. Eventually you will reach another large door.

Wield your blessed spirit shield and make sure you have the four spirit sigils in your inventory. The shield and the sigils will be placed on the door, and it will open. Now get through the rest of the dungeon until you finally reach Zhuman. After a long conversation, the battle will finally begin. Defeat Zhuman. Go back to Zi Cochan and talk to Golsharu to receive your reward.

Rewards

 * 6 quest points
 * Access to Desert Island volcano area
 * Ability to spin bloodflax into dragon crossbow strings with 80 Crafting
 * Ability to make magic stocks with 80 Fletching
 * Ability to make dragon crossbows with 80 Fletching
 * Ability to wield dragon crossbows with 81 Ranged
 * Access to Desert Island volcano area
 * Ability to spin bloodflax into dragon crossbow strings with 80 Crafting
 * Ability to make magic stocks with 80 Fletching
 * Ability to make dragon crossbows with 80 Fletching
 * Ability to wield dragon crossbows with 81 Ranged
 * Access to Desert Island volcano area
 * Ability to spin bloodflax into dragon crossbow strings with 80 Crafting
 * Ability to make magic stocks with 80 Fletching
 * Ability to make dragon crossbows with 80 Fletching
 * Ability to wield dragon crossbows with 81 Ranged
 * Ability to make dragon crossbows with 80 Fletching
 * Ability to wield dragon crossbows with 81 Ranged