# How much of a large's creature's space must be above a pit before they fall?

Scenario: The party encounters large skeletons. The combat map has a lot of squares marked as (possibly) bottomless pits. Each skeleton takes up four squares. If they are forced towards the edge, how many of their squares must be on pit squares before they can fall (i.e. gets a saving throw to avoid falling)?

1 square (i.e. a corner of their space)? 2 squares (i.e. half their space)?

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All of it. But it may end up squeezing if they are partially over the pit.

If only part of a creature's space is over a pit or precipice, the creature doesn't fall (Normally a creature ends up in such a position as a result of forced movement.) On the creature's next turn, it must either move to an unoccupied space that is at least as large as it is or squeeze if it wants to remain on the edge of the drop. (PHB 284, RC 209).

So it will have to squeeze if it wants to stay (or is prevented from moving). But the squeezing does not take effect until it's turn. It will not fall unless it is completely over the pit.

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Most appreciated. – Misma Jun 12 '13 at 14:13
A sufficiently large creature might not be able to squeeze. Does it then fall? – starwed Jun 12 '13 at 14:18
@starwed Not per these rules. It seems they'd be allowed to squeeze in less space than is normally allowed (perhaps to model them clinging to the edge of the precipice). – wax eagle Jun 12 '13 at 14:19
Eh, the rules present two options: moving or squeezing. I don't see that they'd allow illegal squeezing any more than they'd allow invalid movement. Now lets take a moment to consider the phrase "illegal squeezing". >_> – starwed Jun 12 '13 at 14:24
@starwed which presents an interesting paradox if a creature happens to also be immobilized, as it cannot squeeze or move if immobilized. I'm honestly not sure what the ruling would be, my guess is: falling; no save. – wax eagle Jun 12 '13 at 15:10

All of their space has to be over the pit.

From PHB1, p284-285:

Falling

• Large, Huge, and Gargantuan Creatures: If only part of a creature's space is over a pit or a precipice, the creature doesn't fall.

The Rules Compendium has the same information on p209 along with the following addition (might also have been added to PHB1 via errata?):

... On the creature's next turn, it must either move to an unoccupied space that is at least as large as it is or squeeze if it wants to remain on the edge of the drop.

All 4 of the skeleton's spaces need to be over the pit to fall, and if the encounter is designed properly there simply aren't any pits that they can fit into.

Also, keep in mind that any creature gets a saving throw to fall prone rather than be pushed over the edge of a pit.

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Curious - Why is it "proper design" to not allow them to fall in any pits? I would think that would be a legitimate tactic in a fight, maneuvering enemies into natural formations to either trap/kill them. – JohnP Jun 12 '13 at 14:20
If it was possible for the skeletons to fall in the pit, then why would they not have fallen into it already? As the Dungeonomicon notes, for a trap or obstacle to be effective, it has to have pretty much impossible for it to backfire against its creators (which is why kobolds like weight-triggered traps). The same applies for obstacles/hazards as well, including pits. If you might fall down a bottomless pit, that's a bad place to fight. If you can't, but your foes can, on the other hand... – Oblivious Sage Jun 12 '13 at 14:30
Thanks for the explanation, I grok now. – JohnP Jun 12 '13 at 17:16
Except that logic, as you've described, only applies when the decision-maker on the obstacles is the same guys you're fighting. In this case, I could very well see an evil cleric who's already got a room full of 2x2 pits (as opposed to custom-making them, then they should be smaller) filling that room with Large skeletons: the room still gives the skeletons some advantage, since they can't be made to fall as easily as most expected enemies could; even mindless, they can be ordered to push enemies in; and if one does fall, the investment is much lower than the cleric's own person falling in. – Matthew Najmon Jun 21 '13 at 0:05
@MatthewNajmon Why wouldn't the cleric then use huge skeletons? If other people have been through there, why is there still a full complement of skeletons in the room? Wouldn't some of them have fallen in fighting previous adventurers? Generally speaking, monsters should be immune to the traps in there area unless there is a specific narrative reason why they're not. If the plot specifically calls for them to be vulnerable, that's fine, but otherwise they should be immune. What ifs have no bearing the matter. – Oblivious Sage Jun 21 '13 at 14:01

Physics can be called it to provide a clue how to model this. Things fall when their center of gravity is not directly over their base of support. So in the case of an otherwise stable object capsizing and falling over an edge, it has to be pushed far enough that its center of gravity is beyond the ledge.

For example, if we push a uniformly dense meter-wide cube over an edge, it will fall just after the point where it sticks out by half a meter.

If roughly you model the animal as a symmetrical object of uniform density (such that the center of gravity is exactly in the middle of the dimensions that it occupies), then it means that it falls in when it sticks over the edge of the pit by more than 50%, similarly to the cube example.

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Except the rules explicitly say that's not how it works. – Oblivious Sage Jun 12 '13 at 20:00
In almost all cases, a creature does not actually take up the physical amount of space they get on the grid. It is just the area of the battlefield that they control and move around inside. Very few human beings are 5 feet wide, for instance. – starwed Jun 13 '13 at 2:48