Potion of amnesia

!
Name	potion of amnesia
Appearance	sparkling potion
Base price	100
Weight	20
Monster use	Will not be used by monsters.

A potion of amnesia (unidentified, a "sparkling potion") is an item which appears in the Lethe patch and SLASH'EM.

Quaffing it will cause you to forget all of the current map, has a 1/3 chance of causing you to forget some level maps, and another 1/3 chance of forgetting some discoveries. If it is non-blessed, it also may cause you to forget some spells. If it is blessed, it will cure lycanthropy and sickness and give you 51-100 nutrition points. Monsters will throw this at the player with similar effects.

This potion cannot be cancelled.

Dipping

Dipping an object into the potion has a number of effects. Objects with positive enchantment may lose one level of enchantment ("Amnesia acts as a disenchanter"). Rustprone objects have a 50% chance of rusting, erodeproof objects have a 1/13 chance of losing their erodeproof status. Blessed or cursed objects will also become uncursed. Magic markers lose 2 + 1d10 charges.

Some objects will also be downgraded to non-magical versions. Many of these changes can be undone using a potion of gain level to upgrade the object. The affected objects are:

Old object	New object
Loadstone	Flint stone
Luckstone
Healthstone
Touchstone
Magic lamp	oil lamp
Magic candle	Wax candle or Tallow candle
Drum of earthquake	Leather drum
Magic whistle	Tin whistle
Magic flute	Wooden flute
Magic harp	Wooden harp
Fire horn	Tooled horn
Frost horn
Horn of plenty

Dipping the potion into a water source will cause it to become a potion of water in one dipping, without the diluted stage. This preserves the beattitude of the potion, and as such may be used as a source of (un)holy water if an appropriately aligned altar is unavailable.

Lethe waters

The Lethe waters affect items and the player in similar ways. SLASH'EM does not fully implement the Lethe patch, but the castle moat is currently considered Lethe water. The castle moat can therefore be used as an infinite supply of potions of amnesia for downgrading objects. Dipping a potion of water into the castle moat will always result in a potion of amnesia.

The Lethe waters have a 100% chance of rusting rust-prone objects (this would be 25% if the object is blessed, but the blessed status is removed first) and a 20% chance of removing erodeproofing from an item. A scroll dipped in the Lethe water has a 10% chance of turning into a scroll of amnesia instead of blank paper.

Throwing

When throwing a potion of amnesia, make sure there is at least one empty square between you and your target - otherwise, you will be subjected to the vapors of the potion, potentially forgetting maps and item identities.

This potion can also be used to pacify angry shopkeepers "Shopkeeper looks at you curiously!". In some circumstances, this can also erase any debt you have. Specifically, when you escape a store with unpaid items or debt, the shopkeeper is considered "robbed", your ordinary shopping debt is erased, any stolen items become yours, and in order to pacify the shopkeeper, you would normally need to give them at least half the amount for which they were robbed, i.e. half the total of your debt and the value of the stolen items. Hitting a shopkeeper with a potion of amnesia causes shopkeepers to forget about being robbed - no matter how much they were robbed for - but does not cause them to forget ordinary shopping debt or unpaid items.

Hitting a non-covetous monster with a potion of amnesia has a 75% chance of making them peaceful (and untame if they were tame) if they do not resist "Monster looks bewildered!". Hitting a flaming sphere or iron golem will do 1d6 damage. Hitting a gremlin will cause it to split, with no other effects. Hitting the Wizard of Yendor will cause you to forget, as per reading a blessed scroll of amnesia. Hitting certain monsters with the potion will produce YAFM and no other effects:

Monster	Message
Medusa	Medusa looks like she's having a bad hair day!
Croesus	Croesus says: 'My gold! I must count my gold!'
Death	Death pauses, then looks at you thoughtfully!
Famine	Famine looks unusually hungry!
Pestilence	Pestilence looks unusually well!

Being hit with the potion has a 90% chance of causing your helmet to be subjected to the effects of the potion (50% chance if the helmet is cursed, as a cursed helmet would benefit from the potion). You will also be subjected to the vapors of the potion, causing you to forget items and spells.

Strategy

The potion of amnesia can be used to uncurse or unbless items, but as they can result in losing enchantment, charges, and rusting, this is usually suboptimal. Drinking the potion is usually bad, and as the appearance is not randomized it is trivial to avoid. Drinking a blessed potion can be used to cure lycanthropy or sickness if no other alternatives are available. The potion also gives a surprising amount of nutrition when blessed, which may be of use for a foodless ascension.

Monsters will throw this potion at you, causing amnesia, so it is advisable to pick up any that you find, even if you do not intend to use them. If you plan on breaking the potion by throwing it, make sure there is an empty square between you and the wall you throw it at. Generally it is better to keep it to dilute, but if you don't have a sack or a handy fountain, destroying it may be preferable, since you will be subjected to the vapors if the potion is destroyed by a fire attack.

Since there is no defense against thrown potions of amnesia, its effects need to be mitigated. Identifying as many things as possible will reduce the likelihood of having actually useful discoveries forgotten. Collect items in your stash and name them. Collect scrolls of identify even if you don't need them. Place spells of little value at the end of your spell list, because spells are forgotten starting from the bottom. Try to read several spellbooks that you intend to forget for the confusion-on-demand they'll provide. Otherwise, you'll have to wait 10,000 turns to reforget them. Keep some equipment to fix your helmet if it gets damaged.

Downgrading objects can also be useful. Downgrading a magical flute, horn, harp, or drum will result in the non-magical equivalent, all of which can be upgraded back to the magical tool with a potion of gain level. This will restore some charges, in case no other method of charging an object is available. "Downgrading" a loadstone will turn it into a flint stone that can be dropped. Downgrading any extra luckstones, touchstones, and all loadstones can provide the player with a healthy selection of flint stones that can be upgraded to healthstones. Having multiple luckstones is rarely useful, but the effects of healthstones stack, and a large stack of flint stones can be upgraded with a single potion of gain level. If the upgrade results in luckstones (50% chance) then the luck stones can just be downgraded again. In all cases mentioned above, the tinker technique can substitute for the potion of gain level.

Beware using this potion in random alchemy - if it explodes you will be affected by the vapors unless you have magical breathing and lack eyes. The nightgaunt is the most suitable form for this, as they are unbreathing, have no eyes, and fly.