Question: Diagonal movement, obstacles, difficult terrain, and threatened area

[Harr]

So here's a question that's been bugging me ever since the "1-1-1" threads. I always figured it would become clear with time but since I'm now getting ready to run KotS and no answer is in sight for me, I'll go ahead and ask:

So we have 1-1-1 diagonals at work here, which I'm fine with. Now, presumably as a consequence of this, under 'Obstacles' in KotS, I get the following rule: "When an obstacle fills a square, you can't move diagonally across the corner of that square."

That's great so far. But the... What about difficult terrain? When a square is difficult terrain (so presumably the terrain "fills" the square), can I diagonally cut across the corner of that difficult terrain square without getting any of the effects of the terrain?? I would think not! But I suspect the opposite.

Similarly with threatened areas. A medium creature threatens a 3x3 square centered on itself. Presumably, the threat "fills" all of these 8 squares around the creature. If I diagonally cut across the corner of one of the corner squares, do I provoke an Opportunity attack?? Again, my logic tells me yes, but I suspect the rule is no.

Finally, if the rule is in fact "No" for both of these, I might just end up house-ruling it to "Yes", does anyone foresee any real problem with that?

Thanks for any advice on this.

 

[Traken]

Don't have any concrete info, but I suspect you're probably right. D&D is a very state-orientated game. You're either in a square, or not. There's no 'between' squares.

As for problems with house-ruling, I don't foresee any major implications or problems. At most, the fighter gets slightly more effective. Just be sure to tell everyone so they're on the same page.

I might actually end up doing this as well. Hmm....

 

[Yaezakura]

I'm suspecting the answer to the questions is no. However, I think I'd advise against houseruling them to "yes", because the rules are fairly realistic as it is.

The reason you can't cut across a corner with an obstacle is because the obstacle is a solid obstruction--you'd be running, for example, right into the corner of a wall.

With difficult terrain, you're barely skirting the corner of it--the portion you actually travel over is small enough to be long-stepped over without difficulty, so it doesn't slow you down (besides, very little difficult terrain would fit the square entirely--the tip of the corner would likely be free of obstruction for a more organic look, and the tile only poses a problem for someone squarely inside it).

As for provoking OAs, by housing yes, you'd effectively be making everyone threaten 13 squares instead of 9--that's giving them nearly half again as much threatened territory, so it's generally bad from a balance POV (especially taking into account things with Threatening Reach). Aside from that, only part of your body would be in the square for a very limited amount of time--not enough for the opponent to draw a bead on you before you're gone.

It's merely speculation, of course.

 

[Harr]

Interesting points - my initial motivation was reports from D&DM players where I heard stuff like terrain really was never an issue because you could just zig-zag all around it without losing any mobility, and also stuff like you could get at the back-row wizards/archers in a single move by zig-zagging around the front-line fighter and just barely making it to the back within your move.

When I saw the solid obstacle limitation I thought, "both of those other problems would be solved with this." But I guess there's no info out there about it yet. I think the fact that's it's an 'in-between' thing speaks strongly to it being ignored by the rules. Maybe it doesn't really matter in the end, since it goes both ways (the monsters can certainly zig-zag just as much as the PCs can).

 

[Yaezakura]

Well, I don't think D&DM players are the best judge. Their maps are static--ours aren't. ^_^ If a DM wants difficult terrain to be a factor, it'll be a factor, because it'll be whatever shape and take up however much room the DM needs for it to do its job.

With the "bypass the tanks" issue... it's a valid concern. Just like in real combat. The enemy force needs to position themselves in such a way to reduce that risk. Taking advantage of difficult/impassable terrain, choke points, multiple defenders spread out to threaten the maximum area possible, etc, to make it so you HAVE to engage the tanks before moving onto more squishy targets.

I don't really think the changes to diagnal movement will detract anything from the game. It's opens up new avenues of attack, sure--but it does it for both sides of the fight.

 

[D'karr]

Difficult terrain only adds additional squares to your movement. An obstacle would be something like a large rock in your path. You can not cut across the rock on a diagonal, you must take that additional square to "round the corner."

Movement "OUT" of a threatened square provokes Opportunity Attacks. So if you cut across the corner the first square is a threatened square. Entering it does not provoke. Exiting that square with anything other than a shift, will provoke and Opportunity Attack.