The weight bridge.
Speak to Lucien in the Flying Horse Inn in the western part of East Ardougne, and tell him, "It sounds like a laugh." He will give you a Pendant of lucien. Equip the pendant, as it is required to open a gate in the temple, and bring a light source. The temple is located south of the Ranging Guild, north of the Ardougne Farm and east of the Fishing Guild; directly west of the Sorcerer's Tower. Climb down the ladder. On this first trip, you should bring only your slashing weapon/knife, light source, and pendant. With additional weight reducing items like Graceful, Penance Gloves or the Spottier Cape from the Hunter skill, it's possible to have all of the required quest items in your inventory, removing the need to bank while still being below 0kg weight.
Once you're inside, if you don't already have Boots of lightness, go through the room (ignore the gates for now), and go down the stairs. It's dark, so you'll need a light source. Go through, slash the web, and grab the Boots of lightness. Equip the Boots of lightness. At this point if you weigh more than -1 kg, you will need to bank your items at the Ardougne bank closest to the temple. If you already have weight reducing gear, you can grab the limpwurt roots as well but make sure you're at most -1 kg.
Then, once you have the Boots of lightness, go back upstairs and go through the north gate into the room of fear with the skeletons in it (you need your Pendant of lucien on to go through).
Obtaining the ice arrows.
Go back out the gate and then to the east to get to the ladder that you climbed down in the first place to access the dungeon (at the dungeon's entrance). On the south-west wall near the ladder is the lever bracket. Use the fragment on the bracket and pull the lever. You can now use the south gate to access the ice chamber.
It is recommended that pures or accounts with low Defence bank before the next part as you will be attacked by level 61 ice spiders. Food or Protect from Melee will help ward off the spiders' attacks. Go through the south gate to the ice chamber. Avoid the spiders, and run into the small offshoots of the main cave. Search each chest, one of them will contain 1-5 ice arrows. After you take them, they will respawn randomly in either that chest or any other chest throughout the room, so keep searching until you have 20-30 arrows. Also, switching worlds resets the chests. The higher your Ranged level, the fewer arrows you will need. Note that Ava's Accumulator will return ice arrows to your arrow slot.
Duelling the Fire Warrior of Lesarkus.
Fire Warrior of Lesarkus
Note: If you already have all the necessary items, you don't need to return to the bank.