L^: mu2, i2, wj2	-	R#: T	-	D^: S
C^: v.s.m (i: v.s)	-	CT: 2	-	S^: None
A^: Creature touched	-	psionic encounter: 25%	-	-
-	-		-	-

Effect: This spell causes the recipient to vanish from sight and not be detectable by normal vision or even infravision.

Of course, the invisible creature is not magically silenced with respect to noises normal to it.
The spell remains in effect until it is magically broken or dispelled,
or the M-U or the other recipient cancels it or until he, she or it attacks any creature.
Thus, the spell caster or recipient could open doors, talk, eat, climb stairs, etc., but if any form of attack is made,
the invisible creature immediately becomes visible,
although this will allow the first attack by the creature because of the former invisibility.
Even the allies of the spell recipient cannot see the invisible creature, or his, her or its gear,
unless these allies can normally see invisible things or employ magic to do so.
Note that all highly intelligent creatures with 10 <correct to : 7> or more HD, or levels of experience,
or the equivalent in intelligence/dice/levels <ie. unintelligent creatures with keen hearing or sense of smell> have a chance to automatically detect invisible objects.

INVISIBLE MOVEMENT
By various magical means it is possible to become invisible and move about.
Invisibility bestowed by a cloak of elvenkind extends to what it covers.
A ring or spell of invisibility offers superior invisibility.
Note that none mask light,
so the invisible character cannot move about with a light source and be unseen,
for the light will be noticed even though its bearer and possibly its source are not.

DMG: "Now I'll sneak up on the monster invisibly!"
How often has this cry rung forth from eager players in your campaign?
How often have you cursed because of it?
Never fear, there are many answers to the problem of invisibility,
and most difficulties will be resolved after you read the following rules && suggestions regarding the subject.

Invisibility is not what most players desire it to be.
It is neither a soundproofing nor an odor preventative.
Normal sound issues from the invisible creature,
just as normal odors do.
Monsters might well be able to hear, smell, or see the invisible character.
Furthermore, the associates of the invisible party are not able to see him or her any better than foes are,
so this can cause problems, too.
Now consider a silence spell and large AREA invisibility cast upon a party.
Imagine the chaos within the area as characters stub their toes on the heels of the person before them,
with the inability to hear anything so that falls,
suggestions as to what should be done, or orders cannot be heard.
Consider also that dust on the floor will betray most invisibility,
as will dust or powder in the air.
Think of a door opening without any visible cause;
will this cause suspicion in the mind of the viewer (particularly when the surroundings are taken into account!)?
You bet it will!

Invisibility spells are broken when attack occurs, but what about devices?
Becoming invisible takes but a twinkling,
but if the party is observed doing so,
there is no reason why an opponent cannot attack with the standard penalty (-4) for inability to see the TARGET.
Likewise, becoming visible takes only a second,
but thereafter the foe is able to clearly observe the attacker for a return of the compliment,
as it must be assumed that it requires a full round to again activate the magic which enables the character to be non-visible.

Invisibility to animals, the first level druid spell, does not allow attack, but it is pretty well proof against stupid animals.
Invisibility devices generally duplicate the spell or else make the user likely to be undetected that turn or round,
indetectability being stated as a percentage chance.
CHECK EACH PERIOD AS APPLICABLE UNDER THE SITUATION.
Dust of disappearance does not negate sound or odor either,
    so it is basically the same as an invisibility spell which allows invisible attack.

Psionic invisibility is a mind control ability ("The Shadow Knows!") which is more similar to the druidic invisibility to animals,
for the affected creature(s) does not notice sounds or odors from the psionic.
Note, however, that this form of invisibility is sharply limited in that it works only on a set maximum number of creatures
according to their combined levels/hit dice.
In no event is the thief ability to hide in shadows to be treated the same as invisibility as regards disappearance
(see CHARACTER CLASSES, THIEF ABILITIES, [Hide In Shadows] for further details).

Finally, we have the consideration of the ability to detect invisible creatures even though they are not actually seen.
This is explainable as the observer's ability to note a minor disturbance in the air -- a shimmering or haze -- or by keen hearing,
and/or keen sense of smell.
The table below gives the probability of detection of invisibility according to level/hit dice.

Note: You may give unintelligent creatures with keen hearing or sense of smell the equivalent of intelligence to reflect detection of invisible creatures.

Check each round the creature is exposed to invisibility. <UA terms: when that creature is the ACTIVE character in combat>
Once detected, the invisible creature will be kept track of thereafter,
as the detector will be able to note the cause.
Any attacks incur the -4 penalty of attacking on invisible opponent, of course,
and the invisible creature likewise is entitled to +4 on saving throws.

Q. What is the chance of detecting
someone who is invisible? (Basic/Advanced)
A. In the Basic D&D rules an invisible
person is simply invisible, until they
attack.
    In the AD&D rules the percentage
chance of detecting someone who is
invisible is given on p.60 of the
DMG.
    In both sets of rules, invisibility does
not alter the amount of noise that
someone or something makes or
mask their scent.
(Imagine #1)

Invisible Opponents: Invisible opponents are always at an advantage.
They can only be attacked if they are attacking or otherwise detected somehow.
These opponents always cause the attacker to attack at a -4 on “to hit” rolls because of the invisibility.
They can never be attacked from flank or rear positions unless the attacker can see them (thus they are, in fact, visible!).

MC: An eyelash && a bit of gum arabic, the former encased in the latter.
 

Wu Jen: This spell causes the recipient to be undetectable by sight, incl.
infravision and ultravision. It does not silence the creature, nor does it prevent
detection by other means. The invisibility lasts until dispelled, whether
by spell or action. Any attacks on an invisible creature are at -4, and the
invisible creature gains +4 on saving throws.
 

QUESTION: Is an invisibility spell cancelled when you
fall on your face from tripping either over your own feet or from
someone else’s number 13’s?

ANSWER: No.
 

Q: Can the recipient of the second-..
level magic-user spell invisibility
see himself? Does an object dropped
by the recipient become visible?
Does an object picked up by the
recipient become invisible? The
book says that any attack will end
the invisibility; does this include the
casting of any spell or just attack
s p e l l s ?

A: The recipient of an invisibility spell is
invisible even to himself. Any equipment
carried by a creature at the time the spell
is cast becomes invisible with the creature.
If the creature puts an item down, the
item becomes visible, but if an invisible
creature picks up a visible object, the
object stays visible. Nondamaging spells
will not make the recipient visible, but any
action intended to harm another creature
will.
(154.96)

ADQ: Can invisibility can be cast on inanimate
objects? If so, can it make light
radiated from such objects invisible also?
ADA: Invisibility only affects a recipient
creature; objects are only affected if they are
"gear" of the invisible creature. No creature
can be the "gear" of another; 1
invisibiliity spell affects only 1 life force.
As to light -- well, that's a sticky one, and
left to the DM's option. We recommend
that all light becomes visible once it leaves
the light source, even though such a source
could itself be invisible (Note: See Issue #3
for more notes on invisibility.)
(Polyhedron #25)

SPELLING BEE

This issue we're going to examine invisibility.
It occurs as the 2nd level
M-U and Illusionist spells Invisibility,
and their 3rd level spells of Invisibility 10' radius;
4th level Illusionist spell
Improved Invisibility;
Potion of Invisibility;
and Dust of Disappearance.

Invisibility is one of the most
misunderstood and misused
of all spells, and
thus is the topic in this first column of its
type. The descriptions are relatively
accurate, but can be a bit hard to understand
fully.

Allow me to introduce some characters
of mine: Felonius is a human M-U
of moderate level and talents. He
and his friend Athelstan, a Ranger Lord,
will demonstrate various spells and spell
effects throughout this series. (Athelstan
doesn't have anything to do in this
month's column, but he's got a contract
for every issue. Smile, Athelstan, and
wave to the nice people. Now go away.)

Let's assume that Felonius is casting
invisibility on himself.  He gets out his
gum and eyelash and starts saying the
magic words, moving his hands in the
proper motions (components V, S, M), and
12 seconds later (2 segments), he disappears.
Everything he was carrying at the
finish -- at the end of the 12th second--
disappears wiht him. He can Now CAST
defensive or misc. spells, MOVE,
etc. without popping in. He can pop in
whenever he wants, though; no other
spells are necessary to break the invisibility.

The same effect applies if Felonius
casts it on his friend Athelstan, except
that either of them can break it at any
time.

If ANYTHING distracts Felonius while
he's casting, the spell will not take effect
in the 1st place. Distractions include
ANY damage to him, failing to make his
save vs. any attack form (charm,
push, etc.), and being roughly moved,
even if no damage results. Thus, if a fellow
party member bumps into him during
the casting (retreating from or moving
to engage an opponent, for example),
well -- so it goes.

So what happens to the items Felonius
is carrying? The term givevn in the spell
description is "gear," and the Area of
Effect is "Creature touched." Therefore,
if Felonius is carrying 800 pounds of
treasure and can barely stand, it all disappears;
but if he's got his familiar (a
mere toad) on his shoulder, the toad will
NOT disappear; it's a separate creature,
and not "gear."

Now we get to the deductions. If an
item made invisible as "gear" remains
invisible when it's put down, there will be
problems. Some Chaotic would, no doubt,
run around making things like rocks and
tables invisible, just to create more Chaos
when others wander into them. Invisible
poisoned spikes would litter dungeon
floors, and death and Chaos would
quickly ruin the world. Therefore, whenever
any item leaves the invisible creature's
possession, it 'pops in.'  Since the
invisibility effect is created at one
precise moment -- the end of the casting
-- there's no reason why an item picked
up by the invisible Felonius would disappear;
indeed, it will remain clearly visible
to all, showing Felonius' approximate
location. This applies whether the item
he's picking up was part of his gear or
not. Follow me?

Can Felonius hide a visible gem he's
found by hiding it under his cloak? No;
the cloak's invisible, too, and will not
block sight of the visible item.

Generally speaking, tricks and traps
involving an invisible item should be very
rare: the spell affects a CREATURE and
gear, and the gear becomes visible when
leaving the creature. However, I think a
Limited Wish (or Wish, or comparable
spells) would make an item invisible.
How does it reappear? Only if it attacks
(?) or is dispelled. So making items invisible
by themselves is neither easy nor
common. (Hallucinatory terrain works
better for hiding items, and is dispelled
by touch.)

If any further disagreements arise on
the effects of invisibility, consider the intent.
When the book says "gear," it means
the normal things the character could
carry. Considering my ruling, a player
levitated a wagon (by spell), then flew up
(spell again) and supported a bit of
the weight himself, he then cast the invisibility,
and claimed that as he was supporting
the mass (physically and magickally),
that it was "gear," and should go
invisible too. Sorry, I replied; he's
stretching things. Use common sense
and "DM's discretion."

Invisibility 10' radius works similarly.
At the finish of the spell (18 seconds after
starting, this time), every creature within
10 feet of the caster disappears, along
with the gear carried by each of them.
This does NOT set up a "power field" of
invisibility (a common misinterpretation)
that you disappear when enteriing and
reappear when leaving. After the casting
is finished, the effect is the same as if
invisibility had been CAST on each creature,
individually. As the spell description
says, "Those affected creatures
which attack negate the invisibility only
with respect to themselves, not others
made invisible." But note that the caster
can, at will (not using any more spells)
break everyone's invisibility, all at once;
the caster can cause 1 or more of the
invisible creatures to "pop in" and let
others remain invisible, if desired.

For example, if an oncming giant entered
the 10' radius just as the spell went
off, and therefore became invisible along
with the party. Felonius could 'pop it in'
and leave everyone else invisible. And
even if Felonius attacked that giant, negating
his own invisibility, the rest of the
group would stay invisible (subject to
their own actions); the caster's attack
only negates his own effect, not that of
the whole group.

Felonius, out with friends on horseback
and seeing enemies approaching,
once gathered everyone around, CAST
this spell, and caused the whole party,
including the horses and gear carried by
them, to disappear, as it was not being carried but
just dragged around.

The illusionist's spell Improved Invisibility
works the same way as invisibilty
while it lasts, except that the invisible
creature can attack without 'popping in.'
Note that you don't get something for
nothing, though; this marvelous effect is
balanced by the low duration of the spell,
as opposed to nearly unlimited duration
of normal invisibility.

Speaking of 'nearly unlimited' duration --
if Felonius doesn't attack (etc.)
after becoming invisible, how long will
he remain so? Although the spelll description
mentions eating, it seems that
food eaten will remain visible through
the digestive process, ending up as tiny
particles forming a human-shaped mist
as the molecules are circulated throughout
the body. A few meals will effectively
negate the effects of the invisibility. Dust
and grime picked up in the course of a
day or so must be carefully washed off,
lest they give the show away. Ever see
the movie?

If you decide that items picked up by
an invisible creature diseappear, be prepared
for the ramifications. A mage could
become the perfect bank robber, if he
could just get near the money. What
happens if he picks up another creature?
Your players are going to try everything,
just be ready.

In my campaign, players quickly realized
the vast added benefits that invisibility
would give a M-U's familiar. I
therefore ruled that familiars don't like it,
at first, although they'll put up with it for
short periods. But if takes weeks of daily
practice before a familiar will feel comforable
riding around invisible on its invisible
master's shoulder. War horses
should have problems in a similar manner,
unless the effect is carefully explained to
them (by way of a speak with animals
spell, for instance). Normal horses won't
like it at all. As a rough guideline, creatures
above animal INT will
cooperate with invisibility (and possibly
make good use of it), and those of animal
INT will not.

A Potion of Invisibility works in exactly
the same way as the spell, except that it
has specified durations, depending on
whether drink all of it or just a sip. It
does NOT give the effect of improved
invisibility at any Time, regardless of how
much is consumed, nor can it create
invisibility 10' radius.

The Ring of Invisibility is quite special;
the wearer can "become invisible at will,
instantly" (DMG). Although it only functions
once per round, it is the fastest
known method of 'popping out' in the
AD&D system. The invisibility itself is
quite normal in effect.

Invisible creatures can be detected
without magick. The DMG
has a table which explains things;
simply, any creature with 7 or more levels
has a chance at "seeing" invisible.
Note that "10 or more levels" is the
phrase used in the PH;
the DMG is more recent, and should be
used instead. Dragons "see invisible"
too, the range determined by their age.
Characters without the experience can
use other means, if they're clever enough,
to counter invisibility in some situations.
For example, an invisible monster in a
small room could be dimly seen by
breaking a bag of flour or soot inside; the
DM should note the danger of explosion
if fire is present (medieval flour mills
often exploded accidentally).

In any of these cases, however, the
invisible creature is NOT clearly seen;
rather, a "shimmering or haze" (DMG) is
detected. Attacks thereafter a -4
penalty on "to hit" rolls, and the creature
gets +4 on all saves while invisible
to the attackers. Felonius' detect invisibility
spell will, of course, reveal the
invisible creature to him completely; but
that effect applies only to him. Felonius
may guide others (like Athelstan;
where'd he go? The woods? Oh, well...),
pointing and talking about where the
invisible opponent is; but even with such
aid, the penalties and bonuses will still
apply. Sadly, Felonius can't CAST a detect
invisibility on anyone else (a thief, for
example); it sure would be nice for that
thief to find all the traps the easy way, but
it can't happen. The book says only the
caster can USE this one.

Dust of disappearance bestows an invisibility
which is not detectable in these
ways; its only flaws are that detect magick
will pick it up, and that <the> dust can be
rubbed off or countered in other ways.

If there is ever a conflict in the printed
information (e.g., MM.55, Invisible Stalker: "invisibility
causes opponents to subtract 2 from 'to
hit' dice rolls" conflicts with the -4 mentioned
in the PH), the
more recent information should be used
to correct the old. MM came first, then
PH, then DMG, DDG, FF. Check the
edition and date of publication, too.
(Polyhedron #3)

R^: 0

SPC^: 3/turn

D^: 1 turn/experience level

S^: None

A^: One level/hit die per level of mastery cumulative

Effect: This discipline closely resembles the invisibility spell (q.v.),
but it is weaker in some ways, more powerful in others.

It enables the possessor to become invisible to creatures with only as many levels or hit dice as the psionic has cumulative levels of mastery:
1 at 1st level, 1 + 2 at 2nd level, 1 + 2 + 3 at 3rd level, etc.
However, psionic invisibility cannot be detected by any form of magic,
only a mind bar being able to prevent the power from operating with respect to that particular creature,
for this power affects minds, not light waves or similar physical manifestations.
 

Q: Does the "Detection of Invisibility" table on p. 60 of the DMG apply to psionic invisibility?
Can a character using the discipline of invisibility attack another creature and still remain invisible to that creature?

A: No on both counts.
    First, psionic invisibility involves mind
control, "not light waves or similar physical manifestations"
(PH, p. 113), and hence cannot be detected by
intelligent creatures the same way they might be able to sense
someone who was rendered invisible by magical means. Someone
employing the mind bar discipline is not subject to this mind
control, however, and thus is able to 'see through' the
deception.
    Second, a character using psionic invisibility cannot attack at
the same time because he must concentrate on the application of
the discipline to maintain his invisible state. Unless otherwise
specified in a particular description, no psionic attack mode or
discipline can be employed while the user's mind is distracted or
engaged in some other decision-making activity.
(78.20)
 

Eyelash, normal (everyday; free): gathering
Gum arabic (uncommon; 2 gp/oz): alchemist, bakery, candy maker, physican
(Gum arabic is a gum resin exuded by various African trees of the genus Acacia. Because it travels well, and has many uses, it is only uncommon.)
    32 gp/lb

Lothar TVNI wrote:
Greetings Gary! First let me say congratulations on lighting a fire under the imaginations of so many people, including myself of course!

In The Dragon #33 Len Lakofka mentions in his "Leomund's Tiny Hut" article that you and he disagreed on certain interpretations on some spells. He mentioned Magic Missile specifically. He wrote about the Invisibility spell but he doesn't mention if you agreed with it or not.

Lenard Lakofka wrote:
Invisibility
While violence causes the instant negation of Invisibility, I think that
other magics do so also. I rule that if a Magic-user is invisible he/she will
become visible in the segment during which he/she discharges a magic
item or begins to cast any spell. Also, an invisible figure can not receive
another spell without negating the invisibility. Thus a figure can be
enlarged, strengthened, hasted and then made invisible, but Invisibility
MUST be the last spell throw or it is negated at once! Note that a figure’s
“gear” is not equivalent to another figure. “Gear” above and beyond
normal encumbrance will not become invisible and will spoil the effect
of the entire spell. Lastly, “gear” can not be passed around to others
and remain invisible. The trick of giving all weapons to the Magic-user
to hold while Invisibility is cast and then passing the invisible weapons
back to the other players is unfair. Invisibility can be used to make an
individual weapon, its scabbard (holder) and belt invisible, of course.
Drawing the weapon will negate the invisibility.
/

I had been wondering since reading this article if this was how you ruled the invisibility spell also.

Thanks!
 

Welcome:)

Len's take doesn't matter al that much, as he isn't the author of the game 8O

Magic missiles always hit, and that's a rule i have never varied from.

I covered all the invisibility stuff over on the EN world boards thread, and in general I agree that any offfensive action,m including casting a apell or picking a pocket breaks the spell. Len could have simplified the "gear" question by simply saying that invisibility covers the person upon whom it is cast as well as all normally worn and carried by the individual.

If that doesn't cover it, come on back.
 

Gary's alternate ruling on invisibility +
 

Quote:
Originally Posted by grodog
Hi Gary---

Over on Dragonsfoot, we're having an extensive discussion about when a 1e invisibility spell/potion ends:

    1. The PC appears before the attack is physically attempted---hence drawing the sword, notching the bow, etc. cancels the invisibility and forces the PC to appear.
    2. The PC appears during/after an attempted attack, whether the attack is successful or not; whether the PC appears in the nanosecond the attack begins or anytime during the follow-through stroke seems to be the center of debate. In either case, a drawn sword or notched bow does not cancel the invisibility, which ends only when the physical attack is attempted.
    3. The PC remains invisible until after an offensive action has been attemped. This can be in the form of a spell or melee attack (or a pick pockets attempt??). The PC is invisible throughout the entire attack attempt. After the attempt is finished, whether successful or not, the PC becomes visible. If PC attempts an attack but misses, the PC still becomes visible. Or, after the offensive spell casting begins, the mage will become visible, whether the spell has any effect or not.
    4. The PC does not appear until a successful attack has been made. If the PC attempts the attack but misses, the PC remains invisible. The original query raised by Paul Stormberg was whether or not an MU's invisibility would end after his attempted fireball spell was interrupted by a giant's hurled boulder.

Can you please clarify which option is correct?

Thanks
 

Option #2 fits the bill perfectly.
When in process of attacking, and that would include picking a pocket, the formerly invisible character appears, the dweomer of the invisibility spell being cancelled thus.
the action takes place before anyne can do anything about it, but the attacker is visable and thereafter subject to counter-measures.

Cheers,
Gary

Questions and answers on illusionary invisibility

From "Seeing is Believing", Dragon 105

Q: If my character is invisible, can he see
himself?

A: Yes.
The spell is an illusion which the
recipient automatically disbelieves -- and
so, for that matter, does the caster of the
spell when the recipient is some other creature.
By the same token, neither the recipient
nor the caster will be immediately aware
of the fact when the recipient becomes
visible to others. If some viewers have disbelieved
and others haven't, the recipient
might forget who can see him and who
can't, which could cause problems.

Q: Does all of my character's personal
equipment become invisible with him?

A: Yes.
The illusion would be useless if a suit
of clothing were seen walking around with
no body inside it. The DM may want to
make a ruling on just how much stuff goes
invisible in this manner; it should not be
more than the character can bear or carry.
The best way to handle this is to define how
far the invisibility "screen" extends outward
from the recipient's body. Anything
that sticks out beyond that point is visible.
About 2' of space would be a good (perhaps
generous) ruling on this.

Q: What happens if an invisible person
picks up an object or puts one down?

A: Since the area of effect of the spell is
defined as "one person," it is reasonable to <reads "Creature touched" above, not "one person">
assume that the things picked up would be
behind the aura of the spell and would
become invisible. This only works for those
things that are small enough to fit entirely
within the prescribed "screen" of invisibility,
and which the recipient of the spell is
able to lift, assuming he intends to move the
object. If he puts something down, and
moves away from it, it becomes visible.
Things don?t become partially invisible; if
an invisible character approaches or touches
a long table, the table remains fully in sight.

Q: Why was no saving throw or chance to
disbelieve the spell given in the rules?

A: The rules provide a chance for certain
characters and creatures to detect invisible
beings, which is equivalent to a disbelief
roll. The Detection of Invisibility Table
(DMG, p. 60), as given, only applies to
beings of at least 7th level (or 7 hit dice) and
at least 17 intelligence. But other factors
besides level and intelligence could come
into play; as stated in the note below the
table, "unintelligent creatures with keen
hearing or sense of smell" can be granted a
chance to detect an invisible creature.
Building on this, it would not be unreasonable
to allow certain creatures or character
races a chance for detection based on some
special sensory characteristic. For instance,
the same "sense" that gives an elf or half-elf
an advantage in detecting secret doors could
also contribute to that character's ability to
detect something invisible. If you agree with
this line of reasoning, you could grant
chances to detect/disbelieve for characters
not accounted for on the table.
Players should speak for their characters
when they intend to try to detect invisibility;
for NPCs, the DM must use judgment
as to when and how often the character
would intend to try. As demonstrated in
examples within some of the following
answers, the DM may allow detection attempts
to be made with varying frequency
and at different chances for success, depending
on the circumstances.

Q: If a party is absolutely sure that there
is an invisible person in a room, can all
the characters in the party receive a
chance to detect the invisibility?

A: A normal chance to detect the illusion of
invisibility may be granted only to characters
who have evidence that an invisible
person is in their immediate vicinity. If no
such evidence exists, no roll can be allowed.
If the evidence persists -- for instance, if
the breathing of an invisible creature can be
heard continually -- then the character
sensing the evidence can be granted successive
rolls (once per round would not be too
often) until he succeeds in seeing through
the illusion. If one character detects an
invisible object or creature, he cannot cause
others to see it as well by simply conveying
the information to them, but this information
would allow a bonus to other characters' attempts to detect it for themselves.

Q: Are members of a PC's party able to see
him if he goes invisible in front of them?

A: Technically, the other members of the
party who see the spell being cast are affected
by the illusion -- at least initially --
in the same way that anyone else would be
affected. Each of them has to successfully
detect in order to actually be able to see his
invisible cohort, but the roll for detection
should be made with a hefty bonus and new
rolls (for those who fail) should be awarded
frequently. The odds are that everyone will
see through the illusion fairly quickly. Alternatively,
to save some dice-handling, simply
rule that all other party members have a
100% chance to detect because the evidence
(they saw the spell take effect on the recipient)
is indisputable.

Q: How does dust of appearance work
with respect to the spell invisibility?

A: According to the DMG, the dust will
reveal invisibility of all forms except the
psionic version. The dust will insure that a
correct picture of the world is getting to the
eyes of the user, and whether that picture
was distorted by illusion or physical bending
of light waves is immaterial. This power
of the dust does not affect the mind of the
user, so psionic invisibility is not dispelled.

Q: When an invisible person attacks someone
it cancels his invisibility. However, if
he is alone with his victim, kills him, and
the next victim doesn't hear the scuffle,
there is no reason that his invisibility
should be cancelled -- right?

A: Like all illusions, invisibility is dispelled
when it (the illusion) comes into contact
with an opponent. The phantasmal force
description (PH, p. 75) says "The illusion
lasts until struck by an opponent," but this
works both ways: When the recipient of an
invisibility spell causes damage or takes
damage in a combat situation, the illusion is
instantly negated for all those who actually
see it dispelled (not just the victim). Obviously,
anyone who encounters the formerly
invisible character later will see him --
because he's not invisible any more. The
duration of the spell is given as "special"
not to imply that the magic is permanent in
any way, but because the duration of the
invisibility depends on how long it is before
the invisible character attacks or takes damage
in combat.

Q: How can the illusion of invisibility be
dispelled if not through combat?

A: The spell will only be negated if the recipient
or caster of the spell wishes it to be so,
or if the recipient is the specific target of a
successful dispel magic or dispel illusion spell or similar magic. <dispel magic might not be effective vs. invisibility: see Gary's note about this>

Q: Are there other actions that reveal the
invisibility?

A: As pointed out above and mentioned
several times in the rules, the spell only
shields the recipient from detection by sight.
Sound, odor, or any tracks he may make as
he moves could all give away the presence
of an invisible character to those who sense
this conflicting information and succeed in
actually seeing the source of the sound,
odor, or whatever. Simply being invisible
isn't much good when it comes to being
detected by certain creatures. A dog, or any
other animal with a good sense of smell, will
locate some invisible creatures by odor
more easily than any human or demihuman
could.