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Improvised Weapons and Terrain Powers

posted Tuesday, February 9th 2010 by Jonathan Drain
Fourth EditionGame Design

RPG blogger Chatty DM made an interesting Twitter post last week about solving the 4E end-of-combat grind that happens when everyone’s down to their at-will attacks. His idea is to increase the efficacy of improvised weapon attacks to the level of “page 42″ damage rolls for terrain-based effects.

Interacting with the environment is something I encourage DMs to make use of. One of the big things in 4E designer Mike Mearls’ earlier works Book of Iron Might and Book of Iron Heroes was the use of attacks or skill checks to interact with the environment, such as swinging from a rope or pushing over a boulder. Even Mearls’ contribution to the Age of Worms adventure path, the third edition adventure Three Faces of Evil, features a precariously-balanced statue which can be pushed over to form a bridge.

Clever use of terrain has been extremely popular in video games that support it. You only have to look as far as Worms, considered by some the greatest Amiga game of all time. Your units in this game can use their environment to take cover, bounce grenades from walls, swing from “bat rope” style grappling hooks, drown opponents, dig trenches for safety, even make difficult shots using the wind to advantage. They can really affect the environment and the environment can really affect them, and that’s just the ticket for an engaging and dynamic game experience.

I spotted a similar rule set in 2009′s Dungeon Master’s Guide II, called Terrain Powers (page 62-63). This formalizes what I think DMs have been doing since the early editions of D&D, and that’s rules for attacking with the environment. There’s a rope bridge attack, for example, where you make an Athletics check to shake the bridge and knock people prone or off the bridge. Strictly speaking you don’t need these rules (and you should be able to rule terrain attacks on the fly as your players come up with clever ideas), but the examples given are an excellent benchmark for balance. This is especially important if you want to publish your own adventures including terrain powers.

Now I love the idea, but one thing about this bothers me. The powers scale with encounter level, so a terrain power that requires a moderate DC Athletics check at level 1 will still require a moderate DC Athletics check at level 25. Your problem is that this gets absolutely ridiculous with some terrain powers.

Take Table of Combustibles, a table you flip over with a difficult DC Athletics check to send fire and poison gas everywhere. At level 30, you’re still struggling to flip over the tables you encounter. What tables are these that require a DC 37 Athletics check to flip over? Giant adamantine tables studded with diamond? Is it bolted to the ground with expensive magic? I’d better get to keep the table as treasure.

Or Swinging Rope or Vine, which requires a moderate DC Athletics check and rewards you with some quick movement. A regular dungeon vine at level 1 asks no more than DC20, but the level 30 vines that Orcus keeps around take superhuman ability to grab hold of. Don’t high level black dragons keep any regular vines around? Are they greasing up all the vines in their lair as a defensive measure?

However, I do like Ruined Wall, which you can push over onto people. I imagine that by level 30, applying an Athletics check to any nearby wall will make it fall whether it was ruined or not to begin with.


  1. Brandan Landgraff

    February 10th, 2010

    It’s all in how it’s presented, of course…

    Swinging Rope or Vine can be flavored differently at higher levels. The vines that Orcus keeps around are tendrils of slippery intestines coated in blood and other fluids that should only be described as “juicy”.

    The table of combustibles at level 30 has much heavier apparati on it to allow the alchemist or wizard to safely brew the far more volatile ingredients.

  2. Jonathan Drain

    February 10th, 2010

    I guess the easy vines all fall down a lot when Orcus tries to swing on them.

  3. Brandan Landgraff

    February 10th, 2010

    Yeah Prince of Undeath does have a lot of free time for that sort of thing. I mean there’s only so much scheming and plotting you can do before you’re bored, and then you have all these minions and stuff to do the dirty work. A bit of Tarzan-swinging is just the way for a demon prince to let off steam.

  4. The Chatty DM

    February 10th, 2010

    It’s all about mechanical abstraction. I too was frustrated about ‘epic Cave Slime’ back when I read the DMG, but have now since realized that as a DM you’ve got to scale the terrain’s fluff with PC level.

    While you might still be using the mechanics of ‘table of Combustible’ at level 25 you cam refluff it as ‘Tipping the Doom-Boiler’ or Ripping open the sleeping Dragon’s gut or something to that effect.

    Like I said back then… if climbing a Castle wall is DC 15 at level 1… it still should be at level 25… but by then, why are you still having PCs climb castle walls?

  5. Andy

    February 10th, 2010

    I suspect you could say part of it is feasability in combat? I mean, yeah you can flip over the table, but flip it over and make it hit an enemy?

  6. Grant Marthinsen

    February 10th, 2010

    I have to agree with your earlier assesment…
    The DC should stay the same, but thats why you are given reasons for this to be difficult. The “juicy” vines for example, or even varying door materials.
    But when my PC’s have just been through a rough fight, or series of, I like to replace that next barred adamantite door with a locked iron one for example, to make them feel like the world isn’t totally against them.
    Even though it is.

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