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 too many objects of a same class at once, such as many scrolls, will cause the items to merge and creates a golem. Thus it is best to limit the amount of similar objects in a single pile and distribute your polyfodder into separate piles in a line that can still be polymorphed with just one zap.

Golem generation can be advantageous when polypiling for gems. This particular set-up tends to produce glass golems, which are guaranteed to drop worthless glass when they die. This helps to identify glass and further your gem-hoarding efforts.

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 on the pile, so 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 count as if it had been read once more. It will fade on reading afterwards if it was read four times (and not already known). Likewise, a wand may count as if it had been recharged, increasing the chance of an explosion if you attempt to recharge it. The only way to "cure" spellbooks too faint to be read anymore is to write a new spell on them with a magic marker.

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. A system shock has a 1/(luck + 45) probability of creating a golem from the destroyed item.

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.

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 will 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 the material lost to golems.

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. 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 etc as side benefit. Magical armor and tools tend to become non-magical before 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 get confused, 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.

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

• If a game has been unforgiving, a good time to consider polypiling is when there are many things needed at once—where 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.

When Not to Polypile

• 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.

After these preparations, make six piles in a straight line, each pile containing a total of four items. 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. 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