Regicide/Quick guide

Starting out

 * Talk to King Lathas in Ardougne Castle
 * Travel through the Underground Pass which can be found on the far west side of West Ardougne. Refer to this guide if you get stuck.
 * Enter the well in Iban's Temple.
 * Exit the cave to the west.

Tirannwn

 * Run through the forest, talk to Idris.
 * Run south, jump the leaves trap, pass the sticks.
 * Follow the path north west until you reach a camp.
 * Talk to Lord Iorwerth.
 * Talk to the elf tracker.
 * Talk to Lord Iorwerth again.
 * Talk to the elf tracker again.
 * Click the tracks a few steps west of the tracker near the blue mushrooms.
 * Talk to the elf tracker.
 * Climb through the dense forest, kill the guard.
 * Go north, pass tripwire and go through more dense forest.
 * Run west then south, talk to General Hining in the camp.
 * Take 2 barrels (you will only need 2 if you plan on completing Mourning's End Part I).

Sabotage

 * Talk to Lord Iorwerth. Read the book.
 * Use both barrels on the tar south of the tracker. (There is a very small area where you can do this, directly south of the tracker's cart near the shore.
 * Take some sulphur, grind it.
 * Use limestone on any furnace.
 * Talk to the chemist in Rimmington. Make sure you have the book in your inventory. (If you don't, the Quest Journal will not update!)
 * Use your barrel of tar on the fractionation still outside (complete this process twice, if you plan on completing Mourning's End I because a barrel of naphta is required for that quest).
 * Operate the still:
 * Click the right half of the tar valve twice.
 * When the pressure dial is on the border between the green and red dial, click the right half of the pressure valve.
 * Add a few coal and keep the heat in the green. Make sure to add the coal in small intervals of roughly 5 seconds.
 * Keep it balanced until the bar at the bottom is full. Close the interface.
 * Grind the quicklime into your pot.
 * Use the quicklime, sulphur and cloth on the barrel of naphtha to make a Barrel Bomb
 * Create a strip of cloth by using 4 balls of wool on a loom. A loom can be found inside the building just west of the Falador cabbage patch (South of Falador city).
 * Use the strip of cloth on the Barrel Bomb.
 * Head to Tyras Camp, and run to the catapult north of the camp.
 * Feed the guard a cooked rabbit. Use the bomb on the catapult.
 * Talk to Lord Iorwerth.

The Lord's message

 * Attempt to enter Ardougne Castle.
 * Talk to King Lathas.
 * Quest complete!