Polypiling

Polypiling is the action of polymorphing a pile of objects in hopes of getting some useful objects as a result. The pile is often referred to as polyfodder. The polyfodder often consists of junk. The polymorph spell is a ray with a random range between 3 and 6 so you can work on several piles at once but keep the things you want morphed most closer.

Polymorphing potions will always yield potions, scrolls will polymorph into scrolls, etc. Unicorn horns are especially popular polyfodder because they may polymorph into other magical tools. Another useful thing to do if you gain polymorph in the early game is to polypile spellbooks.

Polypiling has its drawbacks. Trying to polypile stacks of too many identical objects at once, such as many scrolls, will cause the items to merge and creates a golem. Thus it is best to separate stacks and limit the amount of objects made from the same material in a single pile, and to distribute your polyfodder into separate piles in a line that can still be polymorphed with just one zap.

Golem creation can help identify glass: polypiling for gems can produce glass golems, which are guaranteed to drop worthless glass when they die. This is usually still a net loss of material.

Polymorphing may also randomly cause a system shock that makes some objects vanish. You will see a message about "shuddering" when this happens. This is more likely when there are more than four objects in each individual stack that makes up the pile, and when a golem is created. That is another reason not to make the piles too big. The system shock is less likely to happen to blessed polyfodder, and more likely to cursed items.

When polymorphing wands and spellbooks, their quality degrades. A spellbook will act as if it had been read once more. If the book's combined read/polymorph-count is four or more and it is a spell you already know, you will be told that the book is too faint to read anymore; if you do not know the spell, you can read it once to learn the spell but it will become "too faint" immedately thereafter. The only way to "cure" spellbooks too faint to be read anymore is to write a new spell on them with a magic marker. Likewise, a wand will count as if it had been recharged, increasing the chance of an explosion if you attempt to recharge it; thus, it is not generally worthwhile to polypile empty wands.

Probability of system shock, object merger and golem generation

The probability of an object being destroyed due to system shock ("shuddering") depends on its BUC status, unless it is a wand:

• Wands: 1/3
• Blessed other item: 1/12
• Uncursed other item: 1/8
• Cursed other item: 1/3

Note that stacks of more than 4 objects double the odds of system shock for those stacks only. A system shock has a 1/(Luck + 45) probability of creating a golem from the destroyed item. Once the game decides to create a golem, even more objects of suitable material are used up.

Also note that if the stack contains more than one object, there is a quantity/1000 probability that the stack merges into one single object.

Polypiling items that belong to a shopkeeper can anger the shopkeeper.

Probability of item transformation

When polymorphing a magical object, the game will try to change it into another random magical object, re-trying up to two times if the replacement would be non-magical. The third item generated will be used, regardless if it is magical. The reverse is true when polymorphing a non-magical object. The upshot is that a magical object has a significantly higher probability than a non-magical object of turning into another magical object. So don't expect many magic markers from polypiling pick-axes and mirrors; you will have much better odds polypiling unicorn horns. The exceptions are potions of water, blank scrolls, blank spellbooks, and wands of nothing, all of which have a high chance of becoming more-useful items of the same type.

Class	Magical -> Non-magical	Non-magical -> Magical
Armour	54%	0.60%
Gem	92%	negligible
Potion	1.70%	41%
Spellbook	negligible	95%
Tool	60%	0.30%
Wand	negligible	93%

Forbidden items

The following items cannot be produced by polymorph:

• magic lamp
• wand of wishing
• wand of polymorph
• potion of polymorph
• spellbook of polymorph

Additionally, wands, potions and spellbooks of polymorph cannot be polymorphed. Artifacts have a 95% chance to resist, but can eventually be polymorphed into normal items. Stacks of more than four valuable gems will never be created.

Strategy

Polypiling is often used to get ascension kit armor (and completed by wishing). Therefore, you might want to collect all those elven cloaks and boots in the game.

Polypiling is most often used by conduct players who need certain items: It can substitute for wishing, prayer/sacrifice benefits, or literacy, and it can be done relatively safely. Generated monsters offer an almost unlimited supply of polyfodder. However, polypiling is time-consuming and tedious. Generally, it is not worth it unless you are trying for conducts, or unless you are looking for many items at once.

Overpreparing is the other common reason for polypiling. This goes for many first ascenders, pacifist characters who wants the most protection, or even an attempt to get an absurdly high score by polypiling rocks into gems.

General Tips

• Never handle both polyfodder and items you want to keep in your main inventory at the same time, and never ever drop anything useful on your polypile line. People have wondered where their bag of holding with all the artifacts went.
• Even if you do not care about shuddering, #name rocks to get stacks of at most four. There is a limit to how many gems can be created.
• A minor point is to max out your Luck to miminize golem creation. That reduces the total material lost.
• Configure autopickup exceptions to pick up good morphs and your want-to-keeps from the pile.

Preparing

• To minimize loss, it is a good idea to mass-bless magical polyfodder, which is much less abundant than ordinary junk. Potions and scrolls can be cancelled so they will stack, and then dipped in holy water. Name and separate them into stacks of at most four items before polymorphing. Only armor and weapons (and wands) retain their enchantment; these should be cancelled if negative before blessing. A large stack of darts can be enchanted to +7 in one go and then polypiled individually for silver weapons or the future Excalibur etc as side benefit. Magical armor and tools tend to become non-magical rather than shuddering, so there is no point blessing them.

• Non-stackables, such as rings, require more work. The most efficient way is with a blessed, confused scroll of remove curse: In a safe location, pick up as much polyfodder as possible but carry no other uncursed items. Then confuse yourself, read a blessed scroll of remove curse, end confusion, and mass-uncurse cursed items via the spell of remove curse at a skilled level. The light blue aura boon when carefully praying on an altar or even another scroll can also uncurse your entire main inventory. This procedure yields 12.5 blessings per scroll on average.

• Unless you will need only one read, name spellbooks individually how often you have read them, and sort them accordingly. Under each pile you intend to polymorph, engrave that number. Any nameless books after the polymorph will count as read one more time. Keep in mind how often you will have to re-read the spells you get.

When to Polypile

Main article: Common polymorphs

• If a game has been unforgiving, a good time to consider polypiling is when there are many things needed at once: the odds of getting at least one of them is improved. For example, if you're looking for a magic marker in particular, getting a tinning kit would be seen as a waste. However, if you were looking for both a magic marker and a tinning kit, the effective odds of getting something you want go up. If you're looking for a horn of plenty, a magic marker, a pair of lenses, and a tinning kit all at once, polypiling unicorn horns begins to look increasingly attractive.
• Potions are attractive to polymorph, due to the ease of creating fruit juice and water, and mass blessing them. Furthermore, with the help of alchemy, a good third of the available potions are useful in some way. While you may not get the potion of enlightenment, or gain level, that you wanted, you are likely to end with various healing potions, levitation, etc, that can be quickly used to work towards what you really want.
• Scrolls are commonly polymorphed for similar reasons. Here, part of the motivation is in doing away with magic markers. It adds a great deal of randomness to the mix, but scrolls are still cheaper than marker charges.
• Magical tools. Unicorn horns are a common fodder, due to the large number of useful magical tools, and the abundance of unicorn horns. (For farmers: revived unicorns have a 5% chance of leaving another horn.) Certainly, the magic marker is generally what most would go for, but in the attempt you might find other goodies: A horn of plenty, which spawns potion you can polypile. A fire/frost horn may also be of help, as may a magic harp or magic flute. This is especially helpful to Tourists or neutral players with the PYEC.
• Magical armor. This mostly to finish off an ascension kit, and most often using the various abundant elven equipment as fodder. This is mostly only useful to (wishless) conduct players, as the castle's guaranteed five wishes are good enough to get all the missing types of armor; furthermore, its armor stores might contain missing pieces.

• A common trick is to polymorph elven armor, which can safely be enchanted to +7, into a +7 T-shirt. The number of +7 armors isn't terribly prohibitive: the blessed scroll of enchant armor (to get to +7) will also bless the armor and reduce the odd of shuddering.

Confidence	Base Chance	25%	50%	75%	95%
Polymorphs	1 in 100	28.62	68.97	137.94	298.07
Shuddering	1 in 12	3.31	7.97	15.93	34.43
Armors needed (est.)	—	3.59	8.66	17.32	37.41

• Rings. This mostly to finish off an ascension kit, and namely, to get a ring of levitation, slow digestion, or even free action if for some reason the RNG wasn't benevolent enough to give the player one. But usually you find those even before the Medusa level. Most other rings are only useful in specific situations, polypiling or not.

• One cheesy trick is to polypile for rings of protection or increase damage, with the intention of eating them. It's possible to get a ridiculously low AC or ridiculously high damage. The former is pointless, other than to sound impressive, because you can reasonably get to -40AC without such mind-numbing busywork, and that is enough to make even a minotaurs barely scrape the polish on your armor. The latter may be for Death farming to a ludicrously high score.

When Not to Polypile

• Wands are generally not worth it. This is mostly because by the time the player has a serious stash of wands, and abundant means to polymorph objects (read: the spell), there is only one wand seriously worth going after: death. But this late into the game, there are only four monsters that it matters on—Pestilence, Famine, Rodney, and the High priest of Moloch. Likely (but not necessarily), you already have enough wands of death do deal with those enemies. Also, polymorped wands will more likey explode if charged again.

• In the midgame, however, it may be worth it. If the player doesn't quite have enough items to make a full polypile line, a square of scrap wands may not make anything that you need, but it might make a wand you've yet to identify (if it has charges left). It may also be that you need a wand's special properties—for example, a wand of fire's ability to engrave a permanent Elbereth square.

• Specific Spellbooks. If you only need one specific spellbook (or a book of polymorph to start with), there are better methods than polypiling: Wizards with sufficient Luck can write one using a magic marker. Anyone willing to do the altar work can get books from their god, especially the last few ones you do not yet know. For spells you do know, polypiling is terrible, as it takes only a few rounds of polymorph to make even previously unread books "too faint to read".
• There are better ways to get various other items. For example, a trident, while normally quite rare, can be found in the death drop of a salamander or a horned devil. A silver saber, very desirable for twoweapon combat, can be found in the inventory of the Minetown watch, or the various captains that show up in the Castle.

After these preparations, individually name stackables to separate them, and make six piles in a straight line, each pile containing a good mix of different types of material. These can be polymorphed in one zap. If you only have a limited number of polymorphs, such as from a wand, you could add more items, but you probably want to wait for the spell.

SLASH'EM

In SLASH'EM, polymorphed items (and monster) can eventually revert back to their original form with time. The in-game term for this, which can only be seen in wizard mode, is "hazy." Hazy items, however, can be "fixed" by dipping them in a potion of restore ability. Upgrading items also fixes them. The transmutation limits the usefulness of polypiling somewhat, as obtaining permanent items requires a commensurate supply of said potions. However, polypiling is still just as useful to obtain items that can be useful right away or relatively soon; for example, a polypiled magic marker can be immediately used to write a few scrolls, and then allowed to transmute back after it is empty.

External links

• Breaking wands, cancelling, and polymorphing in NetHack 3.4