Hunllef

Hunllef is a safe-zone and you will not lose items upon death.

Preparation

First you will need to obtain an Enhanced Crystal Key from Crystal Slayer or off another player.
For Hunllef you will need to take 2 combat styles. So grab your best ranged setup along with melee or mage.
Prepare your inventory with your Enhanced Crystal Key, an overload potion/ combat potions, 2 Super Restores/ Prayer potions, and fill the rest of your inventory with your best food.

To get there Teleport -> Bosses -> Hunllef and you will arrive in a dungeon next to a cave entrance.
Equip your ranged gear first as Hunllef is usually protecting against melee when you enter.
Your Enhanced Crystal Key will be consumed on entry, so do not enter without ranged ammo or runes otherwise you will have to teleport out to bank, losing your valuable Enhanced Crystal Key.
Pot up and pray Protect from melee and enter the cave.

The Fight

Hunllef uses 2 attack styles, Melee and Magic. His magic attack shows as a spread of white splashes therefore use Protect from Magic, if he isn't using this attack then pray
Start attacking and keep a look out for when his attack style changes and pray accordingly.
Around every 100 damage dealt Hunllef will then activate his prayer to protect from the combat style you're using. So switch to your second combat style and keep attacking.
It's a fairly straight forward fight but he can deal good damage if you lose focus.

Hunllef's magic attack.

Rewards

Upon killing Hunllef you'll be rewarded with Crystal shards and a Hunllef's Chest Key.

The key can be used on Hunllef's Chest at ::crystal

Potential chest loot.