Scroll of cleansing

The scroll of cleansing is a members only Dungeoneering reward, and can be purchased for 20,000 Dungeoneering reward tokens. It requires a Herblore level of 49 and a Dungeoneering level of 49, although it requires at least level 56 Dungeoneering to earn enough tokens to buy it. Once used, the scroll will disappear, giving the player the following permanent effects, known as the wasteless herblore ability:


 * A 1 in 8 (12.5%) chance that the player will make a potion twice as fast as usual.
 * A 1 in 10 (10%) chance that when adding a herb to a vial of water or coconut milk, or secondary ingredient to an unfinished potion, it will not be used up, leaving the player with an extra ingredient. This effect also works with juju potions, combination potions and extreme potions. This can be extremely advantageous considering Juju herbs must be grown by the player at a limited rate, and that an overload may be saved if making a combination potion. (The potion saved while making a combination potion or overload is random, as any of the potions are considered to be secondary.)

Although there is only a 10% chance to save an ingredient, the scroll saves on average 1/9 of ingredients when re-using the saved ingredients. This is because each saved ingredient also has a 10% chance of being saved again. For example, if 1,000 ingredients are used, 100 should be saved because of the scroll. However, the 100 saved ingredients also have a 10% chance of being saved, so after using them there would be 10 more. Likewise, on average 1 of the 10 ingredients saved from the 100 would be saved. This adds up to an expected 11 $1/9$ % rate of herb saving when the savings are compounded. For example, if you wanted to create 1,000 potions, you would normally need 1000 herbs or 1000 secondary ingredients. However, with the scroll of cleansing, you only need 900 herbs or 900 secondary ingredients. This results in a savings of 100 herbs or 100 secondary ingredients. Thus the savings rate is 1/9.

Players who have purchased the scroll and are making potions in large quantities may find it more efficient to withdraw 15 unfinished potions and 13 secondary ingredients each load, rather than 14 of each. Doing so with a Beast of burden and 2 secondary ingredients inside it will allow players to select 15, otherwise they can only select a maximum of 13 at a time. Although, since the saved ingredients will need to be re-added to new potions, some prefer to just withdraw 14 of each, bank everything after making the potions and then repeat.

The following are not affected by the scroll:
 * Tea
 * Guam, Marrentill, Tarromin, and Harralander tars
 * Barbarian potions

Trivia

 * When this item was released, players quickly found that it did not affect all types of potions. On 1 February 2011, this problem was fixed as stated in the patch notes.
 * On the in-game Dungeoneering rewards guide, it is labeled by its original concept name, "Wasteless Herblore".
 * When a player buys this scroll from the Rewards Trader, it will appear on their Adventurer's log.
 * Unlocking the scroll of cleansing's ability is one of the requirements needed to get a trimmed Completionist cape.
 * When you save wyvern bonemeal, with the scroll of cleansing while making Super Prayer potions, it leaves an extra empty pot in your inventory or on the ground. This is because the way the scroll is programmed, it does not technically save you an ingredient; it simply creates an additional secondary ingredient of the same type to your inventory.
 * Once the scroll is read, it cannot be bought again. However, multiple scrolls may be bought as long as the ability hasn't been unlocked.