Rules for combat on a steep hill

[VerastheBrujah]

Today I'm running a D&D 3.5 session, and my players are likely to attack a convoy on a road that runs along a steep hill (roughly 45 degrees). If they act as I expect them to, they will position themselves in the treeline above the road and attack with ranged weapons-- the undergrowth and slope will make it almost impossible for their targets to come up the hill and engage them. While the PHB and DMG both have a lot of information on fighting at an angle and for cover, there are two rules questions that I have not yet been able to find the answer to.

1) The group of NPCs that they are attacking will want to take cover behind wagons and return fire with crossbows. Is there a rule for leaning out from behind cover and shooting, while not actually leaving their safe square? Or will they have to step out from behind the wagon, shoot, and then wait a full round before they can step back behind the wagon to reload?

2) How should I handle the distance of ranged attacks? If there is a horizontal distance of 30 feet to a target on a battle grid, there would also, by definition be a 30' difference in the vertical location of the attacker and the target. Should I treat the distance for purposes of range increments and cover as 30 feet, or should I use the Pythagorean Theorem to determine the actual distance that the arrow (bolt, javelin, etc.) traveled between the attacker and the target? I'm not concerned about this affecting the flow of the game, as all I have to do is put 30 into an XL formula and it will return the hypotenuse instantly-- in this case 42.4, rounded to 40'.

Thanks for your help

[myancey]

1) The group of NPCs that they are attacking will want to take cover behind wagons and return fire with crossbows. Is there a rule for leaning out from behind cover and shooting, while not actually leaving their safe square? Or will they have to step out from behind the wagon, shoot, and then wait a full round before they can step back behind the wagon to reload?


There are rule listings on cover. For the guys hiding behind the wagon, I'd probably give them at least partial cover. I don't remember if cover rules translate into miss chances or AC bonuses though. But I'd say only partial cover because to stay in their square and fire, they obviously have to have line of sight to the party.



2) How should I handle the distance of ranged attacks? If there is a horizontal distance of 30 feet to a target on a battle grid, there would also, by definition be a 30' difference in the vertical location of the attacker and the target. Should I treat the distance for purposes of range increments and cover as 30 feet, or should I use the Pythagorean Theorem to determine the actual distance that the arrow (bolt, javelin, etc.) traveled between the attacker and the target? I'm not concerned about this affecting the flow of the game, as all I have to do is put 30 into an XL formula and it will return the hypotenuse instantly-- in this case 42.4, rounded to 40'.


I would probably house rule something rather than using the Pythagorean theorem. For example: Give the people with height advantage a +1 to attack and a -1 for those on the lower end of the slope.

The +/- will accomplish close to the same effect as using the theorem...give or take a +/- 1. That's akin to what you do for increased range increments anyway.

[Thrice Dead Cat]

Quick and dirty way to do it would be to treat climbing up the hill as difficult terrain, maybe make going downhill cost ~.5-.75 normal movement, use the rules for high ground bonuses to-hit. The SRD probably has more on this.

[VerastheBrujah]

Thanks for the ideas.

After all the thought and research I put into it, they took a different tactical approach, and it didn't even matter. They flanked the NPCs on the road and only used the hill to ensure that the caravan couldn't run away.

Go figure.

[DonEsteban]

Still interesting questions. I don't know of any rules handling distances in 3D, so you should try to use real distances. At a 45° angle, multiply by 1.5 or 7/5, at a 30° angle by 6/5. As always, simplicity and playability beat accuracy. So if you think this isn't fun and slows down play too much, simply ignore height. If you're talking about a slope of a hill (as opposed to, say, an area with high buildings), you could also just assume that the grid already includes the effect. Unless there are too many differently sloped areas on your map...

Concerning cover:

To determine whether your target has cover from your ranged attack, choose a corner of your square. If any line from this corner to any corner of the target’s square passes through a square or border that blocks line of effect or provides cover, or through a square occupied by a creature, the target has cover (+4 to AC).

...determine line of sight by drawing an imaginary line between your space and the target's space. If any such line isn't blocked, then you have line of sight to the target. The line isn't blocked if it doesn't intersect or even touch squares that block line of sight. If you have line of sight on a target, you can see to cast a targeted spell on it, shoot it with a bow, and so forth.

Rules compendium also allows "improved cover", doubling the AC and Reflex save bonuses and granting improved evasion to creatures behind such cover, including "a creature peering around a corner".

Whether or not you allow "leaning out from cover and shooting" is open to interpretation. I think you should usually allow it, but it should be symmetrical: If they can shoot at me, I can try to shoot at them (though cover rules apply).

[HalfDragonCube]

Try to add in something saying that if something is prone and helpless then it starts rolling down the hill at 10ft/round or something like that.