Sacrifices are an essential part of most religious traditions.
These offerings to the gods serve to indicate reverence and a willingness to serve in any way needed.
As such, normal sacrifices must be made regularly,
as gestures of thanks for victory in battle,
good fortune in finding treasure,
or any generally good occurrence.

Over and above the standard type of sacrifice is the sort used when a cleric wishes to call on his or her deity for a “miracle.”
A miracle is a spell higher in level than the normal limit of the cleric in question.
If a god has been favorably impressed by the piety of his servant, he will grant — on a one-time-only basis — the ability to cast a spell “miraculously.”
This miracle spell will generally be sufficient to accomplish the requested or desired purpose, because the success of a miracle reflects directly on the competence of the god.
If a god’s miracles aren’t enough to do his will, he isn’t much of a god. Of course, this doesn’t mean the cleric will necessarily USE the spell to his or her, best advantage.

What constitutes a decent sacrifice?
There are three types:
    * inanimate,
    * animal, and
    * sentient.

Inanimate: Inanimate sacrifices are either
objects of intrinsic value such as gold, gems, fine wines or oils,
or rare spices or scents; or objects of symbolic value such as an
idol or image of the god, or something related to the mythology
of the god. The symbolic objects must be consecrated before-
hand. A good example of this is druid’s mistletoe. It’s symbolic
of the permanence of life and natural things, regardless of the
appearances. It is consecrated by the ritual collection method
(gold, sickle, catching in a bowl, etc.).

Intrinsically valuable objects increase the chances of the god
granting a miracle by 2% for each standard measure of material.
Each DM must determine these standard measures for his cam-
paign. They might be 100 gp in coin, an equivalent-value gem, a
cask of wine, 5 drams of perfume, etc.

Symbolically valuable objects are specific to each campaign,
and their increases to the probability of being granted a miracle
should be determined individually by each DM.
In no case should the increase be more than 5% for each symbolically valuable object in the sacrifice.

Animal: Animal sacrifices are those animals not considered either
sacred || unclean by the god. In general, each animal sacrifice
increases the chance of a miracle by 2%; if the animal used is
especially favored by the god as a sacrifice, it adds 3%. Such
animals must be ritually dedicated to the god immediately be-
fore being killed. Just shouting, “FOR (GOD’S NAME)!” and slicing
won’t do.

Sentient: Sentient sacrifices are thinking creatures, of an alignment greatly divergent from the cleric’s.
They increase the chances of a miracle by 5% each.
An attempt must be made to convert any sentient sacrifice to the cleric’s god.
Only upon the failure of the attempt to convert will the sentient count as a sacrifice.
Those of lawful or good alignment must diligently work at this conversion attempt.
Others needn’t be quite so zealous. As with all sacrifices, sentients must be sacrificed according to strict ritual.

Increasing the amounts of a sacrifice raises the chance of being granted a miracle.
However, in no case will the chance of a miracle be greater than somewhere around 50%, no matter how many sacrifices are made.
Of course, there’s no reason a DM must tell the player that.

Once a cleric has sacrificed as much as he or she feels necessary, d% are rolled to see if the miracle is granted.
Whatever the outcome, the sacrifices no longer can be counted toward the next attempt.

If a cleric attempts to gain miracles too often (more than
perhaps once a year or so), the max. psb. probability
will go down 5% with each successive attempt (i.e., the next
attempt will be no more than 45%). If the probability gets down
to 20%, a check must be made (if the miracle isn’t granted) for
the god’s wrath. The chance of god’s wrath starts at 50% and
increases by 5% for each subsequent miracle attempt, success-
ful or not. Eventually, the god’s going to get mad.

Obviously, miracles must be carefully prepared for and closely moderated. They will never happen on the spur of the mo-
ment. That sort of activity is called divine intervention — and
that might happen once in a long campaign.

And there you are. Oh, you don’t think this sort of thing would <happen>
in your campaign? You’re sure? (Light the votive candles,
boys, start chanting quietly, and hand me the ceremonial
dagger...)

You’re sure?