nethack spoiler site http://www.nethack.de/
Maintainer: Sascha Wostmann (sascha@nethack.de)
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From: Bruce Cox <bruce@maths.usyd.edu.au>
Date: 08 Sep 1997 13:05:10 +1000


Game luck will affect your chances of:

    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 hell
    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 a 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/getting gold and gems from throne (Luck >= 5 maximises number
        of gems)
    getting good things from a magic fountain (natural luck >= 0 required;
        natural luck >= 4 desirable)

    finding secret doors, 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 polymorphed objects destroyed
    having a split off long worm remain tame/peaceful

So, yes, it affects your fighting ability,  but it does not affect your
dodging ability nor your resistance to magic.
    


Is there a cap on how high luck can go?

Yes.  Natural luck ranges from -10 to 10.  A luckstone will give you
either extra luck (an additional +3) or reduced luck (-3).  A comment
claims that on moonlit night, the maximum for natural luck is 11,
but I don't believe it---all that happens is a routine is called to
add one to your luck but which will not exceed 10 afterwards.



How much luck is worthwhile?  

I.e., should I just try to chuck half a dozen named (but not identified) 
gems?  Or would it be worth my while to identify 50+ gems and throw them 
at the poor unicorn?

The higher the better for some things (like hitting a monster).  But you
definitely want it to be positive to avoid nasty things like having
your wand of wishing tell you "Unfortunately, nothing happens."