What exactly does this do, how is it used, and should i put some of my theif's points in it?

It does what it says, Detects Illusions. Some pesky mage cast Mislead? Have your thief hack at the image with the detect button highlighted (attack and then highlight; won't disrupt attacking) and watch it fade away before it gets killed. Can't target an enemy mage because of Improved Invisibility? Attack with your thief detecting and watch him reappear. Tired of all those fr*ckin' Mirror Images? Poof. Also helpful in the circus tent for spontaneous werewolf vanishing.

The only real problems with it are the short (almost point-blank) range, and only sweeping once per round. If some thief drinks an invis. potion, he'll probably hit you with his backstab before you detect him. But it is still very nice against illusion-employing mages, and cannot be blocked by any spell. I'd wait a while, though; things like lockpicking, traps, and stealth come first.

To think I played the game at least ten times without knowing how to use this skill... anyways thanks for the explanation Fel!

Ohh it would be very useful against annoying tactics mages and liches who have SI:Divination!

I always wondered how this actually worked, thanks in advance Fel!

Felinoid knows everything!!! :banana:

I never use it, because I think it is a waste of skill points, but I will reconsider it carefully.

Have your thief hack at the image with the detect button highlighted (attack and then highlight; won't disrupt attacking) and watch it fade away before it gets killed.Huh?

Is that the same "detect button" used for traps?
:confused:

It is very useful indeed. If I am playing a non-bounty hunter thief I will normally raise my core thief abilities (open locks/detect traps/hide & move) to a usable level and then start pumping all of my points into detect illusion.

Yes, it is the same button as detect traps.

thanks fel I didnt know about the point blank range so that is very interesting.