See the invisible

See the invisible is a status effect used in all game versions. 
It is almost exclusively used by the game engine's Artificial Intelligence scripts assigned to Non-Player Character creature files.
The exception to this usage is when the player summons a Planetar or Deva (including Dark/Fallen versions), as well as party summoned Elemental Princes.
Also, a player summoned Nishruu has the ability as well. Summons from Cacofiend, Summon Fiend and Gate also, but those can't be directly controlled by the player.
The effect is never added to any equipment, item, spell effect, or ability that the player will have access to.
==Mechanics==
This effect is almost always added directly to the creature file as an inherent "always on" ability available to the creature.
The game developers (and mod authors) assign this effect to a creature who is deemed necessary or must be able to sense party members and other creatures that are invisible, without having to cast or apply some kind of divination spell effect in order to do so.
This effect will allow the creature to whom has the effect code assigned to see any creatures that are invisible, sanctuaried or under some kind of Stealth. The creature is still subject to normal detection range limitations. The effect does not remove the state of invisibility, it simply is ignored by the AI script as if the detected creature were not hidden at all, just like if they were plainly visible.
The Non-Detection effect has no influence on this effect.
This effect allows the targeting of any invisible/hidden creature in detection range, and even if the creature is under Improved Invisibility. This includes weapon and spell targeting. 
A creature that has the see the invisible ability suffers no to-hit penalty when striking invisible (or Improved Invisible characters), because the target is detected and targetable.
The See the invisible effect is typically given to powerful creatures or those that have supernatural abilities. It can sometimes be provided to AI controlled creatures that must be able to initiate dialogue with the player's party, even if they are invisible/hidden - for plot or scripting purposes.
There is no method in the game available to the player to prevent or block this effect.
==Notes==
Some AI controlled creatures equip the SEEINVIS.ITM in lieu of having this status effect placed directly in the creature file as an innate ability. Also, in some cases, the creature file and this item are both included with See the invisible ability, making the item redundant - example Cambion (Watcher's Keep).
As this ability doesn't remove the State: Invisible or State: Improved Invisibility it doesn't prevent or affect in any way a character's bonuses from those states. So, the 4 point THAC0 provided from a first strike from invisibility (or multiple strikes from Mislead) is still retained. The 4 points Saving throw bonus is also retained by the character under Improved Invisibility. Perhaps this isn't a technically correct in-game application, but it is a limitation from the game engine's interaction and execution of code involving States.
== Gallery ==
OG DL Follows.png|The Demilich (Watcher's Keep) follows Aerie out of the crypt - she is invisible with the equipped Staff of the Magi, yet the creature can See the invisible.
Category:Non-player powers