Thanks go to jevan027 for writing this quest guide
Well, I'll start from the begining... This will all be assuming you don't have the Trollheim Teleport, since I didn't. The Splitbark Armour is really important because it's the only armour which provides some melee defence while also giving some mage attack. Don't bother unless you have some...
Trip 1
Inventory:
* - equiped
Follow your typical path west then south of Burthorpe through Tenzig's house and out his back door. This puts you on the short-cup up the mountain (from the Troll Stronghold Quest). Climb up the rock pile behind the second goat and go east at the fork. Continue following the road until you get to a gate. Turn on Protect From Melee and open the gate.
Step is Complete.
( Done)
You may be challenged by "Dad" once you attempt to walk through this area. No worries since you have protection prayer on. This battle is very quick with fire bolt! Once you defeat him or if he does not attack, turn off your Prayer and continue through the next gate.
Step is Complete.
( Done)
Run through this small section until you see a cave entrance. Go though the entrance which leads to a horse-shoe like room. Continue running through the room to the other side (not far) and go through the exit.
Step is Complete.
( Done)
Turn off run and walk around the outer most ring of the circle you appear in until you see a yellow dot on your screen. STOP!
Step is Complete.
( Done)
Turn on Protect From Range, and set your speed to run. Continue through the outer ring until it branches to the north west. Follow the north western branch. Turn off Protect From Range, but leave your speed to run. (It's all about to get drained anyways...)
Step is Complete.
( Done)
Continue along the path until you get to another gate. You encounter a troll child. Talk to the child, USE cake with the child, and then talk to him again. He tells you that someone froze his parents. You can attach the Fire Bolt spell to your Battlestaff now.
Step is Complete.
( Done)
Turn on Protect From Melee and go though the gate. ** You should notice your stats will start to drop and you will take 1 damage constantly from here until you leave this whole area.
Step is Complete.
( Done)
Kill 5 trolls with the Fire Bolt spell. (I've heard the level 124's are easier than the level 120's, but I turned on Auto-Retaliate and just killed whatever attacked me.) Keep a close eye on your Prayer, Hits, and Magic levels. If your Magic level drops below the required level for the spell your using (35) then auto-cast will turn off. The best way to manage everything is to keep your "stats screen" up and keep an eye on all the things. Use a stat restore if necessary, but you may not need it. Eat something if that 1 damage hits you enough to worry you.
Step is Complete.
( Done)
Once you've killed 5 go ahead an teleport to Varrock (it requires level 25 to cast, and you will make sure your Magic is above 35 anyways). Once at Varrock, teleport to Falador.
Step is Complete.
( Done)
Trip 2
Inventory:
* - equiped
Walk from Burthorpe to where the troll child is following all the steps from the first trip. (Dad wont attack you this time, so no need to turn on Prayer.) Turn on Protect from Melee while walking through the trolls this time, but make sure Auto-Retaliate is OFF.
Step is Complete.
( Done)
Climb through the cave, south east of the gate, and continue along the trail (leave on protection prayer). Walk through the wolves, continuing north until the wolves stop following you. (You should see a yellow dot with a flashing arrow near it.) Once you see the wolves stop TURN ON PROTECT FROM MAGIC.
Step is Complete.
( Done)
Click on Auto-retaliate if you have time, and start attacking him. He will still hit you for up to 23 with melee, but he will freeze you often too also causing damage. While your frozen take the opprotunity to eat. But make sure you keep a close eye on Hits, Prayer, and Magic levels. Drink Super Stat Restores often, since it both restores your Magic level (you splash less often) and restores 1/3 of your total Prayer. This should be a tough battle even doing all this perfect, I had 1 shark left.
Step is Complete.
( Done)
Once he's dead, he'll drop 2 Chocolate Cakes, and a Super Stat Restore. Turn off Prayer if you haven't already. If you have less that full health after having eaten the cakes teleport out of there (you won't have to fight him again, so don't bring so many stat restores).
Step is Complete.
( Done)
Continue along the path until you get to an icy path. Put on Spiked Boots and walk along the path. You WILL take damage while walking along this path. It's long and I took along the lines of 40-50 damage along the way (no probelm with full health).
Step is Complete.
( Done)
You will see 2 ice blocks in front of you. Go ahead and attack the blocks (10 hits each) until you've freed both parents. Talk to them. You will be teleported to the bottom of the mountain (where you will not receive any more damage) where you will eventually get the diamond.
Step is Complete.
( Done)
Walk or teleport out. (Since I didn't teleport after I killed the one guy, I was low on stat restores AND prayer, so getting back through the rock-throwing trolls was a bit of a problem...)
WOOT! Your done! Hope this helps a bit...
Continue with the quest as directed in the main guide.