Requirements

You need to complete the Dragon Slayer 2 quest beforehand to be able to access Rune Dragons. 

Inventory

• Poisoned dragon dagger. If you can afford it, bring a Dragon Warhammer instead.
• Two doses of super combat potion.
• Two doses of extended super anti-fire potion.
• Four prayer potions.
• Death runes.
• Astral runes.
• Earth runes.
• A digsite pendant.
• Some teleport to house.
• A couple of doses of stamina potion.

Melee Gear Setup 

• Slayer Helmet.
• Fire Cape.
• Amulet of Torture. An Amulet of Fury and an Amulet of Glory are both excellent and cheaper replacements. 
• Peaceful Blessing.
• Dragon Defender. Using an extended super anti-fire potion is the only way you can wear this. If you don’t want to use this potion, you can bring a Dragon Fire Shield and a regular anti-fire potion. 
• Bandos Chestplate. You can replace it with a Torag platebody. 
• Bandos Tassets.
• Dragon Hunter Lance -> Ghrazi Rapier -> Zamorakian Hasta.
• Barrows Gloves.
• Insulated Boots. You need to wear insulated boots when killing Rune Dragons because they have an electricity attack that will otherwise hit you extremely hard. 
• Berserker Ring (I).

Rune Dragon Location

Rune Dragons can be found in Lithkren Vault, and to get there, you have two main routes. 

If you haven’t unlocked the pendant yet, teleport to the digsite and drink a dose of your stamina potion right after.

Remember to bring the digsite pendant with you. Quick travel to the barge guard that stands right by the Digsite barge. Talking to him, with quickly teleport you to Fossil Island.

Once there, drink another dose of your stamina potion and run towards the transportation site that is on the western part of the island. When you are there, find Jardric right by the shore. He will take you to another location, head north, and then northwest. You will find a building along the path, take the stairs and then run south.

Climb down the trapdoor, take the staircase, and you will be already in the lair. You will have to use the digsite pendant on the machine in the passageway.

Keep running north until you encounter the giant doors, click them open and find the Rune Dragons to your right, behind the gates. Keep running north and then take the first east, and that’s where you will find the machine for the digsite pendant. 

That will unlock the teleport.

Once you have done that, you will be able to use the pendant to teleport yourself to Lithkren. If you have already unlocked the pendant, you can save yourself all the previous processes and teleport directly to Lithkren. 

When you get there, head north and climb down the stairs, click open the giant doors, and this time enter the gates to your right to access the rune dragons.

How to Kill Rune Dragons

You don’t need any special skill set to fend off these dragons because they are straightforward to kill. Make sure that you keep using your vengeance and your special attack on your dragon dagger, and you should be perfectly fine.

The first thing you will have to do is pass the barrier to the room where the dragons are. Before you do, make sure to drink a dose of your super anti-fire potion and your super combat. Remember to turn on your quick prayers, which should be set to protect from magic, piety, and preserve.

Once you have done that, go in and start attacking the rune dragons. Be mindful of the special attack that they have.

It resembles an electricity type of attack, so if you stand in one spot without moving, it will constantly hit you. Run away a few squares from where you are to avoid being hit by these attacks.

There are some other attacks that you won’t be able to doge no matter what you do, so keep an eye out for your health, prayer points, and extended super anti-fire. 

• If you use the RuneLite Client it will tell you exactly how much time left you have on your super anti-fire. Each dose lasts about six minutes.

Drink a super combat as well as you keep attacking the dragons. As you will see, they are effortless to kill.