Cleansing crystal

A Cleansing crystal is an item used to cleanse the Corrupted Seren Stone in the Hefin cathedral in Prifddinas. It can be purchased from Hefin monks for coins each or obtained via pickpocketing the Hefin workers.

If a cleansing crystal is used completely, without interruption, it will provide 9,800 Prayer experience. This is a cost of coins per experience. It takes two minutes for a crystal to be fully drained. Up to 30 stones can be used in an hour, providing around 294,000 experience an hour, at a cost of coins.

Alternatively, when the Voice of Seren is illuminating the Hefin Clan district, a cleansing crystal will give 20% more experience, for a total of 11,760 experience. This is a cost of per experience, providing 352,800 experience per hour at the same total cost.

Experience is gained during three stages in the following amounts :
 * 2,100 (2,520) immediately when starting to cleanse a crystal
 * 19 chunks of 275 (330) every 6 seconds while cleansing (starting 3 seconds after the initial experience)
 * 2,475 (2,970) when finishing a crystal (3 seconds after the final small chunk of experience)

An additional 5% experience can be gained if under the effects of a perfect juju prayer potion or perfect plus potion. The experience received can also be increased by wearing the first age outfit and activating the salvation, corruption, or harmony aura. Generic experience boosts--including bonus experience; clan avatars; and the wisdom, enlightenment, and festive auras--also boost experience as expected. During the February 2015 Bonus XP Weekend, the experience gained was doubled, unlike other special prayer training methods such as using player-owned house altars.

If a crystal is fully cleansed while wearing the Tirannwn quiver 3 or 4 and there are more crystals carried in the inventory, the next crystal will automatically be used to continue cleansing. This can lead to training with minimal interaction, if large numbers of crystals are bought in advance.

The player should be careful when clicking while a cleansing crystal is being used. If a misclick or other action occurs that may interrupt the process, the crystal will vanish and the player will not gain the remaining experience. One can chat, rotate the camera, and use most interfaces without interrupting the process.

An alternative method of using crystals is to repeatedly restart the cleansing process for the initial experience only. With this method, there are 4 seconds between each crystal being consumed, giving 2100 experience each. At maximum speeds, this results in about 900 crystals per hour consumed, giving approximately experience per hour at a cost of  per hour ( per experience). During Hefin Voice of Seren, this increases to experience per hour (reduced to  per experience).

Trivia

 * Before a Ninja update on 5 January 2015, the cleansing crystal cost 130,000 coins and provided 9,300 experience.