Chapter 5 - Extraordinary Senses
Invisibility
Invisibility can come from several sources. Almost all are treated as if the spell Invisibility were in effect. Invisibility blocks all forms of visual spotting for the character or item that is invisible. Characters with Ultravision or Infravision can not spot invisible things. Radar or X-ray vision is similarly blocked.
An invisible creature is invisible to everyone, including itself. This is normally not a great difficulty; most creatures are aware of their own bodies and don't need to see their feet to walk, etc. However, when attempting detailed actions (for example, picking a lock or threading a needle), invisible characters have serious problems, suffering a -3 (or -15%) penalty to their chance of success. This does not apply to most spellcasting.
Second, invisible characters are invisible to friend and foe. Unless care is exercised, it is easy for a visible person to blunder into an invisible companion. Imagine a fighter swinging his sword just as he realizes he doesn't know where good old invisible Merlin is standing! The problem is even worse with a group of invisible characters—characters crash and tumble (invisibly) into one another, all because nobody can see anybody. It would be like having a roomful of people play pin-the-tail-on-the-donkey all at once!
The Spell - Invisibility
This spell causes the creature touched to vanish from sight and be undetectable by normal vision or even infravision {note:includes Ultravision}. Of course, the invisible creature is not magically silenced, and certain other conditions can render the creature detectable. Even allies cannot see the invisible creature or his gear, unless these allies can normally see invisible things or employ magic to do so. Items dropped or put down by the invisible creature become visible; items picked up disappear if tucked into the clothing or pouches worn by the creature. Note, however, that light never becomes invisible, although a source of light can become so (thus, the effect is that of a light with no visible source).
The spell remains in effect until it is magically broken or dispelled, until the wizard or recipient cancels it, until the recipient attacks any creature, or until 24 hours have passed. Thus, the invisible being can open doors, talk, eat, climb stairs, etc., but if he attacks, he immediately becomes visible, although the invisibility enables him to attack first. Note that the priest spells bless, chant, and prayer are not attacks for this purpose. All highly Intelligent (Intelligence 13 or more) creatures with 10 or more Hit Dice or levels of experience have a chance to detect invisible objects (they roll saving throws vs. spell; success means they noticed the invisible object).
The material components of the invisibility spell are an eyelash and a bit of gum arabic, the former encased in the latter.
Some other spells that can invoke Invisibility include:
Invisibility 10 foot radius This spell confers invisibility upon all creatures within 10 feet of the recipient. Gear carried and light sources are included, but any light emitted is still visible. The center of the effect is mobile with the recipient. Those affected by this spell cannot see each other. Any affected creature moving out of the area becomes visible, but creatures moving into the area after the spell is cast do not become invisible. Affected creatures (other than the recipient) that attack negate the invisibility only for themselves. If the spell recipient attacks, the invisibility, 10’ radius spell is broken for all. The material components are the same as for the invisibility spell
Improved Invisibility This spell is similar to the invisibility spell, but the recipient is able to attack, either by missile discharge, melee combat, or spellcasting, and remain unseen. Note, however, that telltale traces (such as a shimmering effect) sometimes allow an observant opponent to attack the invisible spell recipient. These traces are only noticeable when specifically looked for (after the invisible character has made his presence known). Attacks against the invisible character suffer -4 penalties to the attack rolls, and the invisible character's saving throws are made with a +4 bonus. Beings with high Hit Dice that might normally notice invisible opponents will notice a creature under this spell as if they had 2 fewer Hit Dice (they roll saving throws vs. spell; success indicates they spot the character).
Mass Invisibility This is a more extensive adaptation of the invisibility spell for battlefield use. It can hide creatures in a 60-yard x 60-yard area: up to 400 man-sized creatures, 30 to 40 giants, or six to eight large dragons. The effect is mobile with the unit and is broken when the unit attacks. Individuals leaving the unit become visible. The wizard can end this spell upon command.
Invisibility to Animals, Invisibility to Undead and other Priest spells are all similar to these.
Detecting Invisible Creatures
Invisible creatures and things are not detectable by normal sight nor by infravision or ultravision. They do not create any significant distortion or haze pattern that can be noted. However, invisible creatures aren't completely undetectable. First, things still cling to them. Flour thrown into the air is useful for this purpose, although it can be easily covered, washed off, or brushed away. Second, the footprints they leave are not invisible. Again, flour on the floor is a good way to spot the movement of invisible creatures. The effects of specific environments are more subtle. Fog and smoke do not reveal invisible creatures. Smoke and fog are filled with swirls and eddies, preventing the creature from being detected. Invisible creatures completely submerged in liquids are also concealed; there is no hollow space or "air bubble'' to reveal the creature's presence. At the surface, an invisible swimmer may be noticed by the observant as an unusual distortion of the waves.
Invisible creatures are not automatically silent. An invisible fighter in plate mail still clanks and rattles as he moves, a dead giveaway to most creatures. They still have scent, so creatures with keen noses can smell them. Indeed, blind, or nearly blind, creatures are unaffected by invisibility. Creatures that rely on other senses than sight are rarely fooled by invisibility, although they may suffer the penalties to attack.
A detect magic shows only the presence of something magical without pinpointing it exactly. Thus, it cannot be used as a substitute for a detect invisibility spell. Furthermore, while an actual light source may be invisible, the light emanating from it is not. This can reveal the location of an invisible character.
When there is minor but sufficient cause for a creature to detect an invisible character, a saving throw vs. spell should be made (secretly if the DM is checking for a player character). A minor cause might be a strange odor, small noise, an object that disappeared when it shouldn't have, or a strange reaction from another person (who has been pushed, kicked, poked, etc., by the invisible character). Such a saving throw should be allowed for each new event. A wolf would get a save when it detected a strange scent, then shortly after when it heard a stick break, and finally a last chance when the character drew his sword from his scabbard. Furthermore, the acuity of the creature's senses and its general intelligence can increase or decrease the frequency of checks.
If the suspicious creature or character rolls a successful saving throw, he detects some small sign of the invisible foe's presence. He knows its general location, but not its exact position. He can attack it with a -4 penalty on his chance to hit. If the check fails, the creature or character is unaware of the invisible opponent until it does something else that might reveal its presence.
Of course, a revealing action (which could range from an attack to tripping over a pile of pots) immediately negates the need for a saving throw. In such cases, the character has a pretty good idea that something is not right and can take actions to deal with the situation.
Finally, even if an invisible character is suspected, this does not mean the character will be instantly attacked. The result, especially for less intelligent creatures, may only be increased caution. Having scented the intruder, the wolf bristles and growls, protecting its cubs. The rattlesnake will give its warning rattle. Even the orcs may only circle about warily, alert for an ambush.
Detect Invisibility When the wizard casts a detect invisibility spell, he is able to see clearly any objects or beings that are invisible, as well as any that are astral, ethereal, or out of phase. In addition, it enables the wizard to detect hidden or concealed creatures (for example, thieves in shadows, halflings in underbrush, and so on). It does not reveal the method of concealment or invisibility, except in the case of astral travelers (where the silver cord can be seen). It does not reveal illusions or enable the caster to see through physical objects. Detection is a path 10 ft. wide along the wizard's line of sight to the range limit. The material components of this spell are a pinch of talc and a small sprinkling of powdered silver.
