SURPRISE

Surprise is simply the unexpected, unprepared for.
Characters can be surprised just as creatures they encounter can.
Noise && light can negate chances for surprise with respect to characters or creatures they encounter.
Surprise is usually expressed as a 2 in 6 chance for all parties concerned,
i.e. a six-sided die is rolled with a 1 or 2 indicating surprise.
Some monsters are more capable of surprising foes than the normal 2 in 6 probability,
and some cannot be surprised as easily, so they have a reduced probability --
1 in 6, 1 in 8, etc. <(In this case, convert the surprise numbers to percentages. 1 in 6 = 16.66, 2 in 6 = 33.33, 3 in 6 = 50, 4 in 6 = 66.66, etc.>

Each 1 of surprise equals 1 segment (six seconds) of time lost to the surprised party,
and during the lost time the surprising party can freely act to escape or attack or whatever.
If both parties are surprised, then the effect is negated or reduced:

Surprise Dice Difference	Lost Segments
0	0
1 (2-1, 3-2, etc.)	1
2 (3-1, 4-2, etc.)	2
3 (4-1, 5-2, etc.)	3

Assume the party of characters, moving silently and invisibly, comes upon a monster.
They have 4 of 6 chances to surprise, and the monster has 2 in 6.
A six-sided die is rolled for the party, another for the monster.
Both sides could be surprised, neither could be surprised, or either could be surprised.
This is shown on the table below:

Party's Die	Monster's Die	Surprise Effect
3 to 6	5 or 6	none
1	1	both surprised
2	2	both surprised
1 or 2	5 or 6	party surprised
3 to 6	1 to 4	monster surprised
1	2 to 4	monster surprised
2	1	party surprised

Noise or light can negate the chance of surprising a monster.
Similarly, if the party is aware of a monster, the party cannot be surprised by it unless it is also aware of them --
in the latter case, it might be able to hide and ambush the party.

If surprise exists, the surprising party can use the time segments to flee/escape,
close,
or attack.
Distance of 10' or less con usually be closed and an attack made in 1 segment.
Physical attacks during surprise situations are also possible on a 1 per segment basis,
whether the form is by weapon, projectile, or method intrinsic to the creature (claws, fangs, etc.),
even a breath weapon USE; magic spells require the proper number of segments of casting time, regardless of surprise.

See also INITIATIVE hereafter.

ADQ: How do you figure surprise
between a ranger (surprises 50%) and an
ettin (surprised only 1 in 6)?
ADA: Carefully. If the surprise roll
(1d6) for normal creatures encountered
is 1-3, a ranger surprises them. Compared
to normal (1-2), that means the
ranger has a +1 bonus. However, the
ettin has a +1 bonus, too, from the
other end (1 instead of 1-2), so the two
effects cancel out; a ranger surprises an
ettin at normal chances (1-2 on 1d6),
while other characters only surprise the
monster on a result of 1.
    Similar situations with other creatures
are handled the same way, converting
everything to modifications of
the roll. Note that a creature may be
listed as "never surprised," but nothing
ever "always surprises."
(Polyhedron #12)