Luck

Your luck affects many aspects of the game. Luck is the sum of two components: regular luck and bonus luck. Regular luck ranges from −10 to +10, changes with events in the game, and may slowly return to a baseline level (see § Luck timeout below). Bonus luck, on the other hand, may be −3, 0, or +3, and it is determined by what kind of luckstone (and certain artifacts) you are carrying. Thus the highest possible total luck is 13, and the lowest possible is −13. A positive value indicates a measure of "good luck" and a negative value indicates "bad luck". However, only a rough idea of your total luck is given in the enlightenment list; the meaning of the messages is as follows:

Total luck	Message
≤ −10	extremely unlucky
−9 to −5	very unlucky
−4 to −1	unlucky
0	luck is zero (wizard mode only)
1 to 4	lucky
5 to 9	very lucky
≥ 10	extremely lucky

Luck timeout

Luck timeout refers to your regular luck slowly returning to zero over time, which it will do under normal circumstances. If your luck is timing out, it is done at a rate of one point per 600 moves (300 if you are carrying the Amulet of Yendor, or if your god is angry). This is counted from the beginning of the game; for example, if you lose one point of Luck on turn 590, you will regain it on turn 600, not on turn 1190.

The baseline level to which it may return is +1 if you most recently started or restored the game during a full moon, −1 if started or restored on Friday the 13th, and 0 if neither or both. A new moon does not affect your Luck at all. These changes in the baseline level do not affect the maximum and minimum values.

Whether your regular luck will return to its baseline level is controlled by luckstones and certain quest artifacts. The effect of these "luck items" depends on the number in your main inventory that are blessed, uncursed, and cursed (see table below).

Number of luck items	Bad luck	Good luck
None	Times out	Times out
More cursed than blessed	No timeout	Times out
Equal cursed and blessed (or all uncursed)	No timeout	No timeout
More blessed than cursed	Times out	No timeout

Note that as a special case (which is possibly a bug), the game will consider you to own no luck items if both the following conditions are true:

1. You have no luckstones, specifically;
2. The number of cursed luck items (other than stones) equals the number of noncursed luck items.

When this case applies, the effect is identical to owning no luck items: no bonus luck, and luck times out regardless of whether the total is positive or negative.

Bonus luck

Bonus luck works in a similar way to the above table, although both blessed and uncursed luck items (referred to as "non-cursed") have the same effect.

Number of luck items	Bonus luck
More cursed than non-cursed	−3 "reduced luck"
Equal cursed and non-cursed	+3 "extra luck"
More non-cursed than cursed	+3 "extra luck"

The same caveats regarding having the same number of cursed as noncursed luck items and no luckstones apply here as to luck timeout.

Ways to change your Luck

Regular Luck is adjusted by each of the events described below, and by the timeout described above. It cannot be reduced below −10 or increased above +10.

Baseline Luck adjustment	Event
+1	Starting or restoring a game during a full moon.
0	Starting or restoring a game during any time when it is neither full moon nor Friday the 13th, or when it is both full moon and Friday the 13th (which cancel each other out).
−1	Starting or restoring a game on Friday the 13th.

Regular Luck adjustment	Event
−2	Break a mirror. (Other glass items have no effect on Luck.)
−n	Breaking n eggs laid by you (at worst −5).
+1	Sitting on a throne (sometimes).
0	Throwing a worthless gem at a unicorn.
−1 to +1 (average 0)	Throwing unknown valuable gem at cross-aligned unicorn.
−3 to +3 (average 0)	Throwing known valuable gem at cross-aligned unicorn.
+1	Throwing unknown valuable gem at co-aligned unicorn.
+2	Throwing named valuable gem at co-aligned unicorn.
+5	Throwing identified valuable gem at co-aligned unicorn.
−1	Hitting a blind floating eye (1 in 500 chance).
−1	Jumping on a Sokoban level before solving the puzzle.
−1	Breaking a boulder in Sokoban before solving the puzzle.
−1	Casting stone to flesh on a Sokoban boulder before solving the puzzle.
−1	Polymorphing a Sokoban boulder before solving the puzzle.
−1	Reading a scroll of earth in Sokoban before solving the puzzle.
−1	Being pulled by a thrown heavy iron ball in Sokoban before solving the puzzle.
−1	Hurtling through the air in Sokoban by throwing something while levitating before solving the puzzle.
−1	Squeezing past a boulder in Sokoban (or walking over one when polymorphed into a giant) before solving the puzzle.
−1	Killing a tame monster.
−1	Killing a peaceful monster (sometimes). See note below.
−2	Killing a peaceful human when you are not chaotic. ("You murderer!")
−5	Killing a co-aligned unicorn.
−5 to −2	Cannibalism (eating your own species), unless an orc or a caveman.
Set to 0	Praying with negative regular luck (sometimes: "golden glow" boon).
−3	Praying on a cross-aligned altar.
−3	Praying before your prayer timeout has expired.
−5	A sacrifice (not your own race) on Moloch's altars in Gehennom.
−3	Being converted by trying to convert an altar.
−1	Unsuccessfully trying to convert an altar, if you were not converted.
+1	Successfully converting an altar.
−1	Sacrificing at another god's altar.
−1	Kicking another god's altar ("Thou shalt pay, infidel!")
−1	Trying to engrave something on another god's altar (also gives "Thou shalt pay, infidel!")
+2	Sacrificing your own race on your own chaotic altar.
−2	Sacrificing your own race on Moloch's altar.
−5	Sacrificing your own race when you aren't chaotic.
−1	Sacrificing an unidentified cheap plastic imitation of the Amulet of Yendor.
−3	Sacrificing an identified fake Amulet of Yendor.
+1	Sacrificing and feeling that your god is "slightly mollified" when your luck is negative.
Set to 0	Sacrificing and feeling that your god is "mollified" when your luck is negative.
+1	Sacrificing and having a "hopeful feeling" when your luck is negative.
Set to 0	Sacrificing and having a "feeling of reconciliation" when your luck is negative.
0 to +5	Sacrificing while your god is pleased.

Prior to Nethack 3.6.0, any luck penalty associated with Sokoban would occur even after solving the puzzle on that level.

Note about luck penalty for killing peaceful monsters, from [1]:

If you manage to kill a peaceful monster without angering it, you have a 50% chance of losing one point of Luck. This is in addition to the Luck penalty for murder described above and the penalty of -5 Luck for killing a unicorn of your own alignment. However, simply killing a peaceful monster with one whack from a melee weapon will anger it before it dies, avoiding this penalty. Most wands and spells will also anger a monster even if they kill it in one zap, but "beam" attacks such as striking or polymorph have a chance of killing without angering, and incurring the additional penalty.

A drawbridge can also kill a peaceful without angering it.

Luck in-game effects

Luck has a part in:

• Making a monster peaceful by untrapping it
• Making a (too heavy to lift) monster peaceful by trying to untrap it ("<monster> thinks it was nice of you to try.")
• Getting an alignment bonus for untrapping a monster
• Accidentally setting off a landmine or beartrap that you are trying to set
• Having monsters get mad when they are trapped by one of your traps
• Setting off a trap you are trying to disarm
• Disarming a shooting trap
• Having chest traps fail to work (flame fizzles out, etc)
• Having chest traps that do work limited to relatively minor effects (especially if you have a unicorn horn)
• Getting any result from prayer (except upset gods—Luck < 0 causes this)
• Getting help from your god when poorly aligned
• Getting a good result from prayer
• Getting the full range of bonus results from prayer
• Being confronted by a minion of the god of the altar you converted (or tried to)
• Causing the gods to be angry when praying in Gehennom
• Having angry gods being less fire and brimstone in their approach
• Hitting a monster
• Hitting a monster with a thrown object
• Hitting a monster with an iron ball when it jerks you back (?)
• Hitting something with a boomerang without it splintering
• Getting good things from thrones (Luck < 0 is sometimes bad, Luck > 0 is sometimes good)
• Destroying or getting gold and gems from throne (Luck ≥ 5 maximizes number of gems)
• Getting good things from a magic fountain (natural luck ≥ 0 required; natural luck ≥ 4 desirable)
• Finding secret doors, hidden corridors, and traps
• Breaking open a door
• Opening a door
• Having your objects resist water damage
• Blessed metal items resisting rust
• Having a wand of wishing succeed (Luck ≥ 0 guarantees this)
• Getting what you wish for (Luck ≥ 0 is pretty much essential)
• Writing a scroll you don't know
• Picking something off the floor by applying your whip
• Attempting a teleport spell in need (guaranteed if Luck ≥ 1)
• Getting at least 2 identifies from a blessed scroll of identify (Luck > 0)
• Having destroyed polymorphed objects create golems
• Having a split off long worm remain tame or peaceful

Natural Luck

Natural Luck refers to your luck without taking the bonus (or penalty) luck from carrying a luckstone into account. Most effects of luck include this bonus, but a handful do not and directly check your luck stat:

• Effects of a magic fountain
• Getting a wish from a throne
• Clones of tame or peaceful monsters remaining tame or peaceful
• Anything that checks your luck for the purpose of changing it, e.g. praying with negative luck to have it reset to 0.

Strategy

You can't do any better than one blessed luck item, so you might as well keep any others in a bag (where they have no effect) as spares in case your main one is cursed. Even an uncursed luck item will be just as good except when your total luck is negative (which is a rare situation, although not unheard of); and even when it is negative, the luckstone will harm you only on turns on which your luck would time out (so you can just bag it for those turns). Cursed luckstones should never be kept in main inventory unless doing so is unavoidable.

Variants

UnNetHack

UnNetHack adds an additional artifact, Luck Blade, that affects luck timeout. In UnNetHack, luck items greatly slow down luck timeout rather than stopping it completely. The modified luck timeout depends on how far your luck is from your base luck: the higher or lower your luck, the less the timeout is slowed. The timeout is calculated every turn, meaning gaining or losing a point of luck could result in that point timing out immediately. This also means that luck timeout is no longer necessarily at multiples of 600 turns if your natural luck has ever been above or below your base luck.

The modified luck timeout is calculated by the following formula. Let l_natural be your current natural luck, l_base be your base luck, and a be 2 if you have the Amulet or your god is angry with you, or 1 otherwise. $\tau = \text{max}(25000 - 200(l_\text{natural} - l_\text{base})^2, 600) / a$

Additionally, Archaeologists gain a +1 bonus to base luck from wearing a fedora. Putting on or taking off the fedora also changes your natural luck accordingly.

|lnatural − lbase|	Timeout	Time to 0	Time from 9	Time from 10	Time from 11
0	∞	0	168 000	173 000	173 800
1	24 800	24 800	143 200	148 200	149 000
2	24 200	49 000	119 000	124 000	124 800
3	23 200	72 200	95 800	100 800	101 600
4	21 800	94 000	74 000	79 000	79 800
5	20 000	114 000	54 000	59 000	59 800
6	17 800	131 800	36 200	41 200	42 000
7	15 200	147 000	21 000	26 000	26 800
8	12 200	159 200	8 800	13 800	14 600
9	8 800	168 000	0	5 000	5 800
10	5 000	173 000	0	0	800
11	800	173 800	0	0	0
12	600	174 400	0	0	0

If you have the Amulet or your god is angry with you, halve all times in this table.

External links

• http://www.spod-central.org/~psmith/nh/gems-343.txt
• http://www.statslab.cam.ac.uk/~eva/nethack/index.html#peaceful

This page is based on a spoiler by Dylan O'Donnell. The original license is:

Redistribution, copying, and editing of these spoilers, with or without modification, are permitted provided that the following conditions are met:

1. The original contributors to any spoiler must continue to be credited.
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