Spot check to notice a tiny hole

[Stalker0]

I plan to have a tiny surprise come out of a hole at the base of a wall as my party walks through a room. What would be the spot check to notice such a hole if:

1) The party was just going room to room fighting the big baddies
2) The party had already encountered enemies in wall slits and holes and so were on guard for such tactics.

 

[Rhun]

How big of a hole are we talking? Tiny as in 6" in diameter, or tiny as in a 1/4" in daimeter?

 

[Infiniti2000]

I'd make the Spot check the same, DC 18 or higher, depending on light conditions. I'd give the party members a +2 circumstance bonus to search for any holes, however. But, I gather they are not gonna have time to search?

 

[dcollins]

To me that sounds more like a Search check. (Spot for big distant stuff, Search for small close stuff.) Stuff coming out of hidden holes is rather trap-ish, which is what Search is for.

 

[VorpalStare]

A search check is called for if they actively search the area containing the little holes (assuming they would find them noteworthy). A spot check is made to notice something you're not actively looking for.

How hard do you want this spot check to be?

My suggestion for setting the DC (for a spot check) is as follows:
Start with a man-sized hole in plain sight (very easy) DC 0.
Modify this up or down depending on the lighting conditions and how well it blends into the walls of the dungeon. (A pitch black hole in a wall of black stone is probably worth a +5 or more to DC, totally your discretion here.)
Apply a size modifier based on the hole's actual size. (See the hide skill for size modifiers, probably +16 for fine = 6" or less, to +8 for tiny = 1' to 2')

If the characters are fighting or otherwise distracted when they enter the room, give them a -5 Spot check modifier.
So a mouse-hole that blends in well with the material in the wall, would be a DC 21 spot check.

If they're on the lookout for such holes, you might consider giving them an extra spot check whenever they enter a new room, if time permits. Extra spot checks cost a move action.

Hope this helps.