Ice Troll King

The Ice Troll King is the boss monster for the The Fremennik Isles quest, and is the leader of the ice trolls. He is located on the northern part of the isles. He uses all 3 combat styles, which includes a Melee attack, a Magic attack that freezes you, and a mighty Ranged in which he will throw rocks at you and a special move which will send you flying across the battleground.

Strategy
The main thing to be careful about is that he attacks using his special attack that knocks you backwards. You should use the Protect from Magic or Protect from Missiles Prayer. Protect from Melee will result in the troll king knocking you into the cave wall for very high damage which will repeat mutiple times, leaving you almost helpless; when you use either of the other prayers, it negates his attack which knocks you back. Wear the Yak hide armour and Fremennik shield (created during the quest). This, combined with the Protect from Magic Prayer, should keep your damage to a minimum as the yak armour will greatly reduce his melee accuracy and the shield will lower his ranged strength. A dragon weapon or better is advised to defeat the King as he has high defensive stats.

One of the most widely-used ways to kill the King is to use the Protect from Magic prayer, along with the Fremennik round shield and the Yak hide armour, because the prayer will protect you from the troll's mage attack, and your fremennik shield and yak-hide armour will greatly reduce the damage (and not just the accuracy) of the troll's melee and ranged attacks, and he will not hit you for more than 10 or 20 life points with each hit.

Another way of defeating him is to simply use a ring of recoil and to stand well away from him. This will cause him to use ranged attacks dealing small amounts of damage to you and him. This method uses a lot of food and may still result in death if you are unlucky.

Also usable is the Protect from Missiles prayer. If this prayer is used, the Troll King can only use magic and close-range (melee) attacks, and you can negate his attack which knocks you backwards. However, he can still freeze you with his magic attack which can be highly annoying and a waste of prayer, and Protect from Missiles has a higher prayer requirement. Bear in mind also that the damage taken from the Magic attack is not reduced nearly as much by your equipment, if at all. For these reasons, Protect from Magic is generally recommended.

Magic is not suggested against the Ice Troll King, even Fire spells and Ranged attacks are also inadvisable. The Ice Troll King is, obviously, a Troll, so he has good defence against Magic and Range attacks - this means that Melee is recommended. Yak hide armour should always be worn, however.

After the Ice Troll King is dead, decapitate him and take the head to the Burgher to show you have defeated him.

For further detail on this and other parts of the quest, see The Fremennik Isles quest guide. Note: the King has a magic attack similar to ice barrage however you can use prayer to protect yourself.