How can you force an incorporeal creature out of a solid surface?

Question

From the PFSRD:

An incorporeal creature can enter or pass through solid objects, but must remain adjacent to the object’s exterior, and so cannot pass entirely through an object whose space is larger than its own. It can sense the presence of creatures or objects within a square adjacent to its current location, but enemies have total concealment (50% miss chance) from an incorporeal creature that is inside an object. ...

If I know that an incorporeal creature is in the area, lurking in the walls/floors, are there any spells or other effects that can force it to emerge where it can be attacked?

Answer 1

A magic weapon that possesses both the brilliant energy and ghost touch magic weapon special abilities ignores nonliving matter yet affects incorporeal creatures normally. Further, according to this Paizo blog post, a weapon that possesses the quality trip—like a halberd or whip—can also be used to perform the combat maneuver drag.

In combination, a creature using, for example, a +1 brilliant energy ghost touch whip can take a standard action to make a combat maneuver check that provokes attacks of opportunity against the square that the creature thinks her foe occupies. She makes a normal combat maneuver check against the foe's combat maneuver defense to drag her foe except that, because of the foe's total concealment, the drag maneuver has a 50% miss chance. If she's successful, she'll pull that incorporeal creature out of its space within the object to the adjacent space where the incorporeal creature can be dealt with normally.

Note, however, that a +1 brilliant energy ghost touch whip—despite costing 72,301 gp—is useless against incorporeal constructs and undead. You'll need a different tactic for ghostbusting or Vision-wrangling.

Of course—because Pathfinder—, casters can do this better: a similar weapon can be conjured with the 2nd-level spell ghost whip.

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Note: I look forward to other answers. This is an already complicated problem made worse by the incorporeal creature having total concealment provided by the object! Also, thank you, ShadowKras, for suggesting the ghost whip spell.

Answer 2

antagonize feat will force it or Paladin challenge evil but it is probably not available in your party if you asked for it

Intimidate or diplomacy if you have a lot of time could be subject to DM approval as a way to taunt a ghost to show itself.

putting a spell on the creature and detect it with detect magic help to find where it is coming from.

With teamwork destroy the barrier and attack the creature can also do the job.

Answer 3

(major edit from my original answer after helpful comments): I'd use the following tactics:

1. If I'm not attached to the property: Disintegrate some parts and replace them temporarily with Wall of Force, to take away where it lurks. But what might work better:
2. Divination spells to find details on the particular kind of creature, perhaps a specific name or alignment. Follow that up with Sympathy cast on an object. The creature has some sort of mind and/or goals: I'd try to lure (or attack) that. For the person who says "This isn't forcing a creature out of a solid surface, it's luring it out," I would say, "Sure. So, replace Sympathy with Dominate Monster, then force it out. The Dominate Monster/ Dominate Person spells do not need to see the target to control it."

The Blink spell says in part:

An ethereal creature is invisible, incorporeal, and capable of moving in any direction, even up or down. As an incorporeal creature, you can move through solid objects, including living creatures

I took that to equate being incorporeal with being ethereal. The two are not the same. To paraphrase this 3.5 answer and what is stated in the comments: Ethereal creatures are on the Ethereal plane. Incorporeal creatures are on the Material plane yet have no physical body.

My original suggestions involving spells like Forbiddance (blocks ethereal travel, is shapeable) or Blink (use Ethereal creature as bait to lure out the target) therefore don't apply and are not helpful. Neither does acquiring a creature with Ethereal Jaunt abilities. I'm mentioning these in this answer only as a warning to others.

As near as I may tell, a cleric's Channel Energy feature is a burst, a burst does not affect a creature with total cover, and an incorporeal creature in the floors would have total cover. So, that's out, too (assuming the incorporeal creature is undead).

Good question and tough problem!

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