This is one of the reasons I always use hexes. Any two adjacent hexes always have a hex line between them, not the line between squares n-s and e-w vs. the point between adjacent square nw-se, ne-sw.
At any rate, I think the rules are clear on this.
You can move diagonally if both squares are unoccupied. Period.
The rules do NOT state that you can only move diagonally if a side square is vacant. That's a house rule. It's a good house rule, but a house rule nonetheless.
If the Villain in the original example did not want the Rogue tumbling past him, he should have been in space 5 instead of space 3.
Christian said:
Will, would you say the same thing if the square labelled '3' were instead an * (5' square of solid rock)? If so, what's the justification for saying that someone can squeeze through the non-existent gap? That the rules let figures move on the diagonals?
If the DM says that there is a large enough gap there for a person to get through, sure.
If he says that there is no gap or the gap is too small, no.
Just like if the DM says that there is a wall between squares A and B, you cannot move through.
* A B *
Christian said:
Sure, if the corner * is empty instead, someone can just walk past (provoking an AoO). But what if it's another enemy instead? Can someone just step between them, because, again, the rules let figures move on the diagonals?
Again, you can walk between them since the rules allow it.
Christian said:
If so, how close do the enemies have to be to close their ranks and prevent non-tumblers from moving through?
Simple. You have to close all paths through.
* 1 2 *
* E E *
* 3 4 *
The enemies here close all paths through.
* 1 2 *
* E 3 *
* E 4 *
The enemies here do not close all paths through.
* 1 2 *
* E 3 *
* 4 E *
The enemies here do not close all paths through.
Christian said:
The rules state the diagonal moves are allowed. They do not state that such a move is *always* allowed when both squares are unoccupied.
The rule is A.
Just because there is no rule B that reinforces A in a given questionable situation does not mean that you can infer that a rule C that countermands rule A must exist.
Neither rule B nor rule C exist, hence, you have to rely on rule A (unless you are rule zeroing it).