In Part Six, we'll examine a few remaining issues that we didn't cover previously.
A battlefield may contain some squares you cannot enter, such as solid walls (if you're corporeal). Sometimes it's possible to maneuver your way through an impassible square after all.
Corners: Corners, such as where two walls meet at a right angle, block movement. You cannot move diagonally past them, though you can trace line of effects for attacks past them. When you attack past a corner, you foe has cover. Most squares that contain foes are impassible to you, but you can move diagonally past them and your target doesn't get cover if you attack along that diagonal. This is because creatures don't completely fill all the space they occupy on the battlefield.
Big and Little Creatures: Fine, Diminutive, and Tiny creatures can freely enter squares that other creatures occupy, even foes (though entering a foe's space provokes an attack of opportunity from that foe). Likewise, a creature can enter another creature's space if it is three size categories smaller or three size categories bigger than the other creature.
Ending Your Movement: When you stop moving, you must be in a space that can hold you. Sometimes, it's possible to move through a space where you cannot stop. For example, you can move through an ally's space, but you can't stop there. If you ever accidentally end your move in a space where you cannot stop, you go back to the last space along your movement route that can hold you. Returning to that space doesn't count as part of your movement.
If you're small enough (or big enough) to freely enter another creature's space, you also can end your movement in that space.
A creature can squeeze through or into a space that is at least half as wide as its space. Movement while squeezing is hampered, and the squeezing creature suffers a -4 penalty on attack rolls and a -4 penalty to Armor Class.
Using the Escape Artist skill, a creature can squeeze into or through a space that's wide enough to admit its head (as a rule of thumb, that's a space a quarter as wide as the creature's face). The squeezing creature can't attack while using Escape Artist to squeeze through or into a narrow space. It takes a -4 penalty to AC, and it loses any Dexterity bonus to Armor Class.
A squeezing creature fills the whole space into which it has squeezed. Smaller creatures cannot pass through the squeezing creature's space. Fine, Diminutive, and Tiny creatures have no natural reach and must enter an opponent's space to attack, technically, that's impossible but here's an unofficial rule to cover the situation: Such creatures can attacker bigger creatures when they're squeezing. The smaller creature enters the squeezing creature's space just long enough to attack. To do so, the smaller creature must be able to fit into the squeezing creature's space without squeezing itself, and the smaller creature provokes an attack of opportunity when it enters the bigger creature's space (unless it cannot attack because it's using the Escape Artist skill). After the smaller creature's attack (or attacks if it uses the full attack action), it must return to the space it left to make the attack, as noted above.
Formerly Helpless Creatures
It's possible for any creature, friend or foe, to end its movement in a space that contains a helpless creature. Unfortunately, it's also possible for the helpless creature to resume functioning while another creature shares its space. Here are some unofficial suggestions for dealing with the situation.
The formerly helpless creature must remain prone in its space until its turn. If another creature still shares its space when the formerly helpless creature's turn comes, the formerly helpless creature must either exit the space, force the other creature out, or contest the space.
To exit the space, the formerly helpless creature must either crawl into an adjacent space that can hold it, or it must stand up and move to an adjacent space that can hold it. Crawling out of the space provokes attacks of opportunity from foes that threaten the space the creature leaves and from foes that threaten the space the creature crawls into (though the creature can tumble as noted in Part 3).
If the creature stands up, it provokes attacks of opportunity from foes that threaten the space where it stands up. It also must use either a move action or a 5-foot step to get into an adjacent space. If it uses a move action, it provokes attacks of opportunity from foes that threaten the space it left.
To force the other creature out of the shared space, the formerly helpless creature makes a bull rush attack against the creature sharing the space. This works just like a normal bull rush, except that if it fails the opposed check to resolve the bull rush, it remains, prone, in the shared space.
To contest the space, the formerly helpless creature can make a grapple attack on the creature that shares the space. If the formerly helpless creature fails to establish a hold, it remains, prone, in the shared space. If it establishes a hold, it can remain in the shared space and continue to grapple just as it would with any other grapple attempt. (Remember that to maintain a grappling hold an attacker must enter the foe's space.)
If the formerly helpless creature is small enough (or big enough) to end its movement in the shared space (see above), it can simply remain in the shared space. If it decides to stand up, it provokes attacks of opportunity as normal for standing up.
Spells and conditions can affect movement (and vice versa). Take a look how in the final part of this series on movement!
About the Author
Skip Williams keeps busy with freelance projects for several different game companies and has been the Sage of Dragon Magazine since 1986. Skip is a co-designer of the D&D 3rd Edition game and the chief architect of the Monster Manual. When not devising swift and cruel deaths for player characters, Skip putters in his kitchen or garden (his borscht gets rave reviews).