Scroll of cleansing

The Scroll of Cleansing is a 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, and is a members only item. Once used, the scroll will disappear, giving the player the following permanent effects:


 * 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 an ingredient to a vial of water or coconut milk, or an unfinished potion it will not be used, leaving the player an extra ingredient.

When using large numbers of ingredients, the scroll's saving ability can appear to have a higher chance than 10% (a bit over 11%). 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 11.11% rate of herb saving when the savings are compounded.

The following are not affected by the scroll:
 * Guam potion (unf)
 * 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. The potions that were not affected were: Guthix balance, Goblin potion, Fletching potion, Weapon poison, Antipoison+, Antipoison++, Weapon poison+, Weapon poison++, Serum 207, Magic essence potion, Sanfew serum, and Super prayer. On 1 February 2011, this problem was fixed as stated in the patch notes.
 * There was a bug where secondaries for Juju potions were not saved when mixing them with unfinished potions. This has been fixed.
 * 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.