Can large creatures "squeeze" through 1-square openings so long as they end up in a location that accomodates their bulk? For example, if a spider (taking up 4 squares) is lurking behind a 3-square long section of rubble with only a 1-square gap between the rubble and the wall, is it trapped there or can the spider squeeze through the opening and move into the larger area on the other side?

I ran into this situation in my first game as overlord (Quest 1: Into the Dark; Area 3) and felt like my spider was rather ineffectual sitting behind the rubble waiting for someone to come his way.

No, there is no "squeezing" in Descent. You can move through allied figures, but if there's rubble or water that makes the corridor too narrow to fit through, you're stuck. The spider in area 3 of the first quest is a classic exampleit can go east towards area 2 by moving diagonally, but it can't go south into area 1.

Thanks for the answer. Looking at the map for that area again I think I just played the room incorrectly. I probably should have held the sorcerer and/or one of the razorwings back with the spider and forced the party to come around the obstacle to attack them all at once. They had to get to the other side to get through the door into the final area so I could have just waited and counter-attacked in force.

Lesson learned.

Well, holding back is usually a bad idea in Descent. Even if you have a group of 4-5 monsters waiting together, it's still usually plausible for the heroes to rush in and wipe them all out in a single turn, so conventional wisdom says that any monster that can attack on the current turn, should attack, even if it leaves your monsters divided or vulnerable. Because if they don't, there's a strong possibility they'll be killed before they get to attack at all.

There are exceptions, though.

Antistone said:

It should be noted that water and pits do not necessarily block movement of large monsters. Only rubble explicitly blocks movement.

zelbone said:

Per the description of pits and large creatures, pits definitely do not block the movement of large creatures, and they are only affected by them if they are fully inside the pit. Water definitely does, as it says under its description that heroes and monsters may not move through it.

James McMurray said:

Can a hero (or creature) jump over a water obstacle? The rules allow for jumping over pits (3 movement points for each space) but make no mention of a similar option for water.

Marximus said:

I only know for sure that heroes can but only if they have Acrobat. Monsters cannot, but for some reason I think Blood Apes can with Leap but could be wrong.

Water blocks all movement, unless you have something that lets you move through obstacles. The FAQ's tongue-in-cheek reasoning is that water is infested with deadly bloodsquids, and nobody is daring enough to risk it.

The only difference between rubble and water is that water doesn't block LOS. For purposes of movement, they are exactly the same.

Big Remy said:

Heroes with Acrobat don't jump over water, they simply skip through it (ie, it costs 2MP to move the 2 spaces, not 3).

Leap-ers ignore all obstacles and enemy figures, so can therefore Leap over impassable water obstacles.