Guthix dragon

The Guthix dragon is the most powerful chromatic dragon in Runescape. It served as guardian for Guthix's altar in The Undergound Pass of Lumbridge. It currently guards the the Amulet of Life, which was created by Guthix. This amulet is extremely powerful, so naturally Guthix used one of his most powerful servants to protect it.

History
When Guthix found out that his brothers, Zamorak and Saradomin where destroying what he made (Gielinor), He had made an undergound maze so that he could pray at his altar. Behind the altar, he had a treasure chest which held the priceless Amulet of Life. Guthix knew that if anyone got past the maze, they would steal the amulet, so he went to the wilderness, the place where his brothers had destroyed the land. There, he found a green dragon, therefore, he picked this color, it was the color of his symbol. The first time he tried to cage it, it bit his hand, then guthix punched the ground so hard that he made a shallow hole, then found out that he wouldn't hurt himself trying to cage the dragon because he had found an energy source. So, he caged the green dragon then after coming back to his altar, he did an enchantment to the green dragon, making it 30 times more powerful than the regular green dragon. After a few moments, Guthix ordered the dragon to guard his altar and the Amulet of Life.

Location
Guthix's altar, in the Underground Pass of Lumbridge

Combat
Guthix dragon uses all three styles in the combat triangle, which makes this dragon more dangerous than the Corpereal beast. It is highly recommended not to fight this dragon for the Amulet of Life, and even if you defeat the Guthix dragon, The Amulet of Life will burn your hands unless if you have a full Guthix armor. When it uses melee, it uses slash or stomp hitting up to 630 life points. When it uses range, it summons stagmites, hitting up to 600 life points. Last, when it uses magic, like all dragons, they use dragonfire. But, it also cast high level earth bolts, water bolts, and air bolts. It can hit up to 700 life points. The most important skills to raise are your attack, strength, prayer, constitution (very impotant), defence, magic, and range

Getting to the Underground Pass of Lumbridge
To get there, you must talk to the Duke Harico to start the quest, Guthix's Altar. If you don't start the quest, when you go to the entrance of The Undergound Pass of Lumbrige, you will get a message saying "There might be scary monsters down there, maybe I shouldn't go." After talking to the Duke, you first go behind the Lumbridge castle. Then you will see the Guthix's symbol very faint on the castle and a hole shaped as Guthix's symbol. But before you go down, ask the duke for a full guthix (requiring 40 defence) because that's how you can get your hands on the Amulet of Life. Also, ask The Duke for a anti-dragonfire shield and a Dragon-stun battleaxe. Using poison is a waste of time, as the Guthix Dragon is immune. If you use any weapon other than the Dragon-stun battleaxe, you will constantly hit zero's.

Rewards
After giving the Duke the Amulet, you get to keep the Dragon-stun battleaxe, the whole guthix armor set, the anti-dragonfire shield, 40,000 XP for defence, attack, strength, and constitution and 130k coins

Trading
After finishing Guthix's altar and dragon slayer part two, the guthix dragon will become a NPC, selling guthix items and will reveal his name, Antheros. you can't fight him again, because you don't actually kill him during guthix's altar, you just stun him for long enough to get the amulet of life and escape. He sells Guthix Armor, dragonhide armor, rare prayer bones, and Guthix dragon eggs for a price of 30m coins.