Invisibility

Invisibility makes a creature undetectable by vision, including darkvision. However, the ability to move about unseen is not foolproof. While they can’t be seen, invisible creatures can be heard, smelled, or felt.

Attacking While Invisible

An invisible creature gains a +2 bonus on attack rolls against sighted opponents and treats their opponent as flat-footed. (Invisibility has no effect against blinded or otherwise nonsighted creatures.)

Invisible creatures cannot use gaze attacks or other abilities which require being seen or looked at unless those abilities create an effect separate from the invisible creature.

Attacking Invisible Enemies

An invisible creature’s location cannot be pinpointed, and it has total concealment; even if an attacker correctly guesses the invisible creature’s location, the attacker has a 50% miss chance in combat.

Invisibility does not, by itself, make a creature immune to critical hits, but it does make the creature immune to extra damage from being a ranger’s favored enemy and from sneak attacks.

Detecting an Invisible Creature

A creature can generally notice the presence of an active invisible creature within 30 feet with a DC 20 Perception check. The observer gains a hunch that “something’s there” but can’t see it or target it accurately with an attack. It’s practically impossible (+20 DC) to pinpoint an invisible creature’s location with a Perception check. Even once a character has pinpointed the square that contains an invisible creature, the creature still benefits from total concealment (50% miss chance). There are a number of modifiers that can be applied to this DC if the invisible creature is moving or engaged in a noisy activity.

A creature can grope about to find an invisible creature. A character can make a touch attack with his hands or a weapon into two adjacent 5-foot squares using a standard action. If an invisible target is in the designated area, there is a 50% miss chance on the touch attack. If successful, the groping character deals no damage but has successfully pinpointed the invisible creature’s current location. (If the invisible creature moves, its location, obviously, is once again unknown.)

If an invisible creature strikes a character, the character struck knows the location of the creature that struck him (until, of course, the invisible creature moves). The only exception is if the invisible creature has a reach greater than 5 feet. In this case, the struck character knows the general location of the creature but has not pinpointed the exact location.

If a character tries to attack an invisible creature whose location he has pinpointed, he attacks normally, but the invisible creature still benefits from full concealment (and thus a 50% miss chance). A particularly large and slow invisible creature might get a smaller miss chance.

If a character tries to attack an invisible creature whose location he has not pinpointed, the attacker must choose the space where the character will direct their attack. If the invisible creature is there, conduct the attack normally. If the enemy’s not there, roll the miss chance as if it were there, don’t let the player see the result, and tell him that the character has missed. That way the player doesn’t know whether the attack missed because the enemy is not there or because you successfully rolled the miss chance.

Invisible Creatures Interacting with the World

If an invisible character picks up a visible object, the object remains visible. An invisible creature can pick up a small visible item and hide it on his person (tucked in a pocket or behind a cloak) and render it effectively invisible. One could coat an invisible object with flour or another sticky substance to at least keep track of its position (until the flour falls off or blows away).

Invisible creatures leave tracks. They can be tracked normally. Footprints in sand, mud, or other soft surfaces can give enemies clues to an invisible creature’s location.

An invisible creature in the water displaces water, revealing its location. The invisible creature, however, is still hard to see and benefits from concealment.

A creature with the scent ability can detect an invisible creature as it would a visible one.

A creature with blindsense can detect an invisible creature but still cannot see it; however, a creature with blindsight can attack and otherwise interact with creatures regardless of invisibility.

Invisible light sources (a burning torch, the light spell, etc.) still give off light.

Invisibility does not thwart divination spells.