Merlin's Crystal/Quick guide

Getting started

 * Talk to King Arthur about joining the round table. (Chat 1)
 * Talk to Sir Gawain nearby. Ask everything you can.
 * Talk to Sir Lancelot upstairs about the stronghold. (Chat 3)
 * Go to Catherby docks and talk to Arhein about riding his ship. (Chat 3-1-1)
 * Hide in the crate north of the candle-maker.

Inside the keep

 * Climb to the top floor.
 * Attack Sir Mordred.
 * Spare his life to discover how to save Merlin. (Chat 1-2)
 * Exit the keep and kill a bat if you don't already have bat bones.

Black candle

 * Talk to the candle-maker in Catherby about black candles. (Chat 1)
 * Goto the house just north of Catherby bank for the insect repellent.
 * Head west and use the insect repellent on a bee hive, then use a bucket to get the wax.
 * Return to the candle maker for a black candle.

Excalibur

 * Talk to the lady of the lake south-east of Taverley on the peninsula. (Chat 3)
 * Get a loaf of bread.
 * Go to Port Sarim
 * Enter the jewellery store to the north.
 * Give the beggar your bread. (Chat 1)

Ritual

 * Go to the Zamorakian temple in south-east Varrock.
 * Check the chaos altar's inscription.
 * Return to Camelot (get a tinderbox) and enter the castle gates.
 * Run to the ritual site at the north-east side of the castle.
 * Stand on the star and light the black candle.
 * Drop the bat bones on the star.
 * The magic words are "Snarthon Candtrick Termanto".

Finishing up

 * Enter the castle and climb the south-east tower.
 * Smash the giant crystal with Excalibur.
 * Talk to King Arthur.
 * Quest complete!