An engraving refers to any form of text inscribed into the ground; the act of engraving refers to any act of inscribing such text in the ground, usually invoked with the command shift + e. The concept includes carving or burning characters into the dungeon floor, writing on the floor with a writing instrument, and drawing in the dust with fingers, wands, etc. This can ostensibly be done by a player to record messages to themselves, and there are also random engravings left in the dungeon; however, the most common use of engraving is to inscribe the name Elbereth.
Engraving techniques may be classed as fast (fingers, wand, non-cursed athame) or slow (other edged weapons, hard gems, gemstone rings). A fast engraving method takes 1 game turn per 10 characters engraved; if you engrave fewer than 10 characters by a fast method, it is instantaneous (this distinction is explained in detail below); otherwise, it takes 1 game turn to write 10-19 characters, 2 game turns to write 20-29 characters, etc. A slow method takes 1 game turn per character.
A non-instantaneous engraving isn't done until after the turn(s) have passed. This is a concern for two reasons: firstly, while players reading a spellbook or eating a food ration will stop when approached by hostile monsters, characters busy engraving will insist on continuing the job; secondly, if you are trying to engrave Elbereth, you are only protected once it is complete. So you can be killed while doing a non-instantaneous engraving (you will be described as 'helpless' in the death reason). Note that none of the engraving counts as being done until all the turns are passed (even if you could have written part of message in less time, no part of the message is on the ground until the whole time has passed); and not even any existing engraving on the floor counts as being present until the time is passed. So doing a non-instantaneous engraving obscures any existing engraving of Elbereth until the turns are complete.
There is therefore a lot of danger in doing a non-instantaneous engraving, so you almost never want to do a non-instantaneous engraving lasting more than 1 turn.
Furthermore, if you are very fast and you know that you will get two turns in a row, you might be able to safely do a non-instantaneous 1 turn engrave: 1 character slowly or up to 19 characters quickly.
Instantaneous engraving is much simpler and safer. It uses only one player turn (so you may get multiple instantaneous engraves per game turn, if fast or very fast, via the usual speed system). Your engraving takes immediate effect, like most other simple player commands; in other words, an instantaneous Elbereth is on the ground before the monsters take their next move. You aren't helpless, and any existing engraving on the ground is not obscured while you engrave.
The engravings themselves may be classified as permanent (will not degrade), semi-permanent (will degrade slowly), or temporary (will degrade very quickly).
Permanent engravings are burned into the floor with a wand of fire or wand of lightning. The wand of lightning can blind you if your eyes are not protected. (Note that the blindness takes effect after the engraving is completed -- you will not increase your risk of misengraving through blindness.) Permanent engravings will not erode from being stood on or walked over, but can be eliminated through techniques such as overwriting them with another wand of fire or lightning, erasing the engraving with a wand of cold, or polymorphing the engraving with a wand of polymorph.
Semi-permanent engravings are carved into the floor with an edged weapon, a hard gemstone, a ring containing a hard gemstone, a wand of digging, or written with a charged magic marker (consuming one charge for every two letters). Engraving with any weapon other than a non-cursed athame will make the weapon dull (reduce enchantment) to a minimum of -3, at which point the weapon is too dull to engrave any more. (If it is not cursed, an athame will engrave forever without dulling. This, and its speed, make it highly prized as an engraving tool.) The weapon ordinarily suffers a -1 degradation for every second letter engraved, but a loophole in how this calculation is done can allow you to write longer messages by breaking the engraving job up into smaller parts: engraving three letters is still only a -1 penalty, so it is possible to use a +0 weapon to engrave three letters, then add three more, and then another three, for a total of nine characters before the weapon is useless, rather than only seven if you had attempted to engrave all at once. This is especially important when engraving the eight-character word Elbereth. Semi-permanent engravings can erode over time as they are walked over or stood upon, but not nearly as quickly as will temporary (finger) engravings.
Temporary "engravings" (actually just drawing in the dust on the floor) with your fingers by responding "-" when asked what to engrave with, or you can use another object such as a soft gemstone, or any wand other than fire, lightning, or digging (certain wands may have undesirable effects on the engraving itself, such as polymorphing it). This is fast, but subject to a 1/25 chance of mis-engraving per letter, and any movement, such as fighting or throwing missiles, will damage the engraving. Even standing still on the engraving will eventually degrade it, as no one stands perfectly still. Temporary engravings can also be erased with a towel. Attempting to write in the dust while polymorphed into a demon or vampire will instead scrawl in blood, which shares properties with writings in the dust.
Chances of engraving
You are not guaranteed to engrave perfectly if you are impaired or writing in the dust. For each letter, you have a (cumulative) chance of messing up if you are blind (1/11), confused (1/7), stunned (1/4), or hallucinating (1/2). If you are writing in the dust (with fingers, a wand, a soft gem, etc.) or scrawling in blood, you have a 1/25 chance of messing up each letter. (When this happens, the letter is replaced by one chosen randomly from among the 94 printable non-space ASCII characters. Thus, there's a 1/94 chance that the letter will be replaced by itself, and another 1/94 chance that it will only change from lowercase to uppercase or vice versa.)
This is not usually much of a concern unless you are engraving "Elbereth", since an error there renders the word powerless (note that attempting to write "Elbereth" in the dust only works about 72.65% of the time as a result). If you can see, you can inspect your work with the "look" command, ':'.
Temporary engravings are eroded by a number of actions. Upon each action, a specified number of characters is picked randomly and corrupted (possibly the same character multiple times). For instance, moving off of a square corrupts between 1 and 5 characters (but not jumping off or onto a square, or moving on to a square). The other actions which affect engravings are: melee combat (3 characters corrupted), throwing/firing (2), kicking (2), applying an axe to the ground (3), zapping a wand of striking or casting force bolt at the ground (2d4), and casting stone to flesh downwards (only affects engraving in stone). Note that normal spellcasting and wands do not erode engravings.
In addition to these actions, every turn, there is a small (1 in 40 + 3 * Dexterity) chance of eroding between 1 and 3 characters on the player's square. Monsters (including pets and steeds), unless sleeping or paralyzed, will erode 1 character in their square per turn. When riding, it is thus impossible to successfully write "Elbereth" in the dust if your steed is faster than you, and you should only rely on permanent engravings which your steed cannot trample.
Semi-permanent engravings only have at most one character corrupted per action. This means that at most two (one for the action, and the small chance each turn) characters will be corrupted per turn. The chance of combat or movement corrupting a character is about 1/13. More precisely, there's 1 chance in (1 + 50/(n + 1}) (where n is the number of characters that would have been corrupted, if the engraving were temporary) that a character will be corrupted, and the following table shows the resulting probability for various cases.
In certain cases associated with magic, even permanent engravings may be eroded; in these cases, there's a 50% chance of no erosion, and a 50% chance that the formula for semi-permanent engravings will be used to corrupt 0 or 1 characters. The magical cases are shown in bold in the table below.
(chance of corrupting 1 character)
- Tiny or handless monsters cannot engrave.
- The epitaphs on gravestones share these properties, for obvious reasons. They are permanent, but can be changed or extended with a hard gem or bladed weapon. This will summon a Ghoul. Elbereth on gravestones is ignored to avoid abusing this, or naming yourself Elbereth to get a permanent Elbereth.
- Using a magic marker to engrave graffiti on the floor is generally seen as a waste of the magic marker, but is also the most common type of writing used for engravings that are randomly generated in the dungeon.
- Burning with a wand of fire or lightning into ice will instead melt letters into the ice, which is like a semi-permanent engraving.
- Engraving may also be used to identify wands.
- When you name an item, it is possible to get a message such as "While engraving your hand slips." The mechanics of engraving and naming are separate and quite different; the message is part of an internal mechanism to preserve the unique naming of artifacts. This is certainly a special kind of engraving, because it is absolutely permanent and requires no tool at all! It also doesn't break the illiterate conduct.
- Flammable items on the square are not damaged by burning with a wand of fire or lightning.
- Cancelling the engrave prompt when using a charged wand will use up a turn and a charge. Cancelling the prompt in any other situation, including an uncharged wand, will not use up a turn.
Chances of engraving
In Slash'EM Extended version v45 and greater, the chances of messing up a letter have been tweaked. Writing in the dust has a 1/30 chance of messing up each letter, and there's a (cumulative) chance of messing up if you are blind (1/25), confused (1/20), stunned (1/15), or hallucinating (1/18). This means the chances of successfully engraving Elbereth while impaired are much higher than in vanilla, making Elbereth a viable tactic even while stunned or hallucinating.
In Slash'EM Extended version v64 and greater, engraving with a wand of digging is much faster; up to 50 characters can be engraved in a single turn, which corresponds to 6 active Elbereths. (In Slash'EM, as well as before NetHack 3.6.0, the effects of multiple Elbereths in a single engraving stack.)
- src/engrave.c in NetHack 3.6.0, line 1059
- src/engrave.c in NetHack 3.6.0, line 1058
- src/engrave.c in NetHack 3.6.0, line 1076
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- src/engrave.c in NetHack 3.6.0, line 1028
- src/allmain.c in NetHack 3.6.0, line 323
- src/engrave.c in NetHack 3.6.0, line 296
- src/engrave.c in NetHack 3.6.0, line 294
- src/monmove.c in NetHack 3.6.0, line 377
- src/monmove.c in NetHack 3.6.0, line 312
- src/dokick.c in NetHack 3.6.0, line 881
- src/dothrow.c in NetHack 3.6.0, line 86
- src/apply.c in NetHack 3.6.0, line 2879
- src/uhitm.c in NetHack 3.6.0, line 403
- src/dig.c in NetHack 3.6.0, line 1164
- src/apply.c in NetHack 3.6.0, line 3004
- src/allmain.c in NetHack 3.6.0, line 323
- src/hack.c in NetHack 3.6.0, line 1215
- src/zap.c in NetHack 3.6.0, line 2785
- src/zap.c in NetHack 3.6.0, line 2780
- src/mklev.c in NetHack 3.6.0, line 847
- src/engrave.c in NetHack 3.6.0, line 522
- src/engrave.c in NetHack 3.6.0, line 460
- src/do_name.c in NetHack 3.6.0, line 598