                                 Altars
                                 ======

                  by Dion Nicolaas (dnicola@cs.vu.nl).

Altars can be quite mysterious to a beginning player. Yet, they are
very important for finishing the game. Here follows the most important
information on altars in NetHack.

Altars can occur anywhere in the main dungeon, sometimes even more than
one on a level. Altars generally don't appear on special levels (like
the Oracle or Medusa's Island.) In the Gnomish Mines there is only one
altar, which is predefined (it is not generated randomly). In Gehennom,
altars are not generated randomly either: there are always three altars
in Gehennom. The following altars are present in each game (from top to
bottom): three altars on the Astral Plane, an altar on the Mines' Town
level in the Gnomish Mines, an altar in the Valley of the Dead, an
altar in Orcus' Lair (the Ghost Town), and an altar in Moloch's Sanctum
at the bottom of Gehennom.

Various quests have their own (predefined) altars in it. See the
quest.map file for more information on these.

When standing on an altar, there are two useful things you can do:
sacrificing and praying. The effect of your actions depends not only on
your luck and your current standings with your god, but most of all on
the altar's alignment, compared to your own.

Every altar has an alignment, which determines to what god it belongs.
The alignment of randomly generated altars is, as expected, random, and
so is the altar in the Mines' Town. The altars in Gehennom are
unaligned, since they all belong to Moloch, the renegade god. On the
Astral Plane there is one altar for every alignment. They are called
"High altars" and the Amulet of Yendor should be sacrificed here to
complete the game.

Praying
~~~~~~~
Praying on an altar is in two ways different from praying somewhere
else. First, if any potions of water are on the altar, the prayer is
also a water prayer. A water prayer on an altar of your own alignment
converts any number of potions of water or unholy water into holy
water. A water prayer on another god's altar makes all water unholy.
Note that a prayer on another god's altar is addressed to that god:
your god is not going to like that, so your luck is decreased by 3, and
your god will become angry and might punish you in several ways.

The second difference with normal prayers is that if you pray on your
own altar, the chance that something nice will happen is significantly
higher. Your god may fix your troubles, uncurse items, give you more
hit points, intrinsics or a spellbook. Also, there is a chance you will
get a hint about the tune you have to play to open the drawbridge of
the Castle. Eventually you can be crowned Hand of Elbereth, Envoy of
Balance or Glory of Arioch (explained further in "crowning"). More than
one of these events can happen as the outcome of one prayer.

Sacrificing corpses (except humans, elves and unicorns)
~~~~~~~~~~~~~~~~~~~
When you sacrifice corpses on an altar of your own alignment, various
nice things can happen. The corpse shouldn't be too old, though: if
your sacrifice is older than 50 moves, nothing will happen. One
exception to this are acid blob corpses, which are never too old.

How much the sacrifice means to your god is based on its value, which
in turn depends on the toughness of the monster. An exception is made
for human bodies if you are human, elven corpses if you are an elf, and
unicorn corpses. These are explained in detail below.

If your god is angry with you, his anger becomes less if you sacrifice
on one of his altars, depending on the corpse's value. Your luck
increases, the amount depending on the sacrifice's value, and you get a
hint about your prayer timeout: if you should not pray yet, you "have a
hopeful feeling", if it is exactly time, you "have a feeling of
reconciliation." If you get no such message, you were already eligible
to pray (and see below).

If you are already in good standing with your god, you might gain an
artifact, depending on your experience level. If you don't gain an
artifact, your luck will increase some more if possible, the increase
depending on the corpse's value.

If you sacrifice corpses on an altar of a different alignment, there is
a chance that you will convert the altar to your alignment. This does
not work for the High altars on the astral level; these can never be
converted. If you try anyway, the god owning the altar throws
everything he has at you.

If your god is angry with you when you try to convert an altar, _you_
will be converted to the altar's god instead. The altar's god accepts
your allegiance, and you have a sudden sense of a new direction.
Conversion is costly, however: your luck is decreased by 3 and your
prayer timeout increased by 300. You cannot convert to Moloch. He
rejects your sacrifice, decreases your alignment and your luck by 5,
decreases your wisdom by 2 and apart from that, your own god will
become angry.

If your god is pleased, the altar might be converted to your god,
depending on your experience level. Your wisdom is exercised, and your
luck is increased by one. If there was a priest(ess) around with the
same alignment as the altar, he or she will become angry. Exactly the
reverse happens if you don't succeed in converting the altar: your
wisdom is abused and your luck is decreased by one. You god won't
become angry as a result of this, though.

Sacrificing humans or elves
~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you, as a human, sacrifice a human corpse, or, as an elf, sacrifice
an elven corpse, on an altar of your own alignment, your god will
become very angry if you're not chaotic. Your wisdom will be abused,
your wisdom will go down by one point immediately as well, and your
luck and alignment will be decreased by 5. If you are chaotic, though,
your luck goes up by 2, your alignment by 5 and a demon lord is
summoned. This demon lord will be peaceful, but in no way useful, since
it cannot be tamed.

If a lawful or neutral character sacrifices a human on a chaotic altar,
the altar will disappear and a hostile demon lord will be summoned.
Again, your god will not like this and punish you as above. If a
chaotic character sacrifices a human at a non-chaotic altar, this altar
will be turned chaotic immediately (such altars are called "cursed").

Human (or elven) sacrifices on an unaligned altar are, strangely
enough, handled exactly the same as on a chaotic altar. An altar cannot
be converted by human or elven sacrifices.

If you are polymorphed into a demon, you find the idea of sacrificing a
human or elf very satisfying. Your wisdom will be exercised, regardless
of your or the altar's alignment, and regardless of what happens next.

After the human or elven effects are accounted for, nothing else
happens. This means you can never please a god by sacrificing humans or
elves.

Sacrificing unicorns
~~~~~~~~~~~~~~~~~~~~
If you sacrifice a unicorn corpse on an altar of the unicorn's
alignment, your wisdom goes down by one point, regardless of which god
the altar belongs to. If you sacrifice a unicorn of a different
alignment on an altar of your god, it's a very good action. Your
alignment goes up by 5.

If you sacrifice a unicorn of your alignment on another god's altar,
you are converted immediately. Again, this will not work on Moloch's
altars, since you can never become unaligned yourself. If you try
nevertheless, your god will become angry again.

After the added effects of the unicorn, the sacrifice is handled as any
other sacrifice. However, the unicorn corpse' value as a sacrifice will
be increased by 3 if your action was good, but set to one if you
converted yourself. If you sacrificed a unicorn corpse on an altar of
the same alignment, its value is decreased by 5.

