21 August 2014

Easy Cover

Hard cover against missile fire is incredibly easy to adjudicate. (For the few who don't know - hard cover will stop the projectile, soft cover merely conceals you. A stone wall is hard cover against pretty much anything, plywood is hard cover against arrows but not bullets, a hedge is soft cover).

Estimate the amount of cover - 1/4, 2/4, 3/4.

Then, when rolling your attack, also roll a d4. If you don't roll higher than the cover amount, you miss, no matter what the d20 says.

Simple, predictable results. Fast to play. Easy to understand. Realistic. Everything you need in a rule.

This is unlikely to be an original idea, but apparently 5e uses an AC modifier, which is a very stupid way to handle cover, and this was my alternative.

EDIT: Caveat - this only makes sense when the marksman's original chance to hit is 100% or less, so that any reduction in target size causes a commensurate reduction in chance to hit. That's not necessarily always going to hold true - I'm sure that I could put 20/20 arrows into an 8ft2 target at 6ft, and 20/20 arrows into a 4ft2 target at 6 feet, but I don't ever see >100% CTH in my games, so I'm unconcerned about that oddity.


  1. How do you account for hard vs softcover? D4 for hard as above but a bigger die for soft cover?

    1. This is just for hard cover. The only effect of soft cover is that you can't see things that are behind it.

  2. So if you're aiming at a guy standing behind a waist-high wall, no matter how great a shot you are, you will never have more than a 50% chance to hit?

    That doesn't seem right. The same skill that lets you narrow your shot to the 2 foot horizontal dimension where he is should also let you narrow your shot to the 2 foot vertical dimension where he's not covered by the wall.

    1. Yes, I edited the post to show that this breaks down if you have a greater than 100% chance to hit.

  3. Your solution assumes that everyone is always aiming at a general location on the target and is happy with a hit anywhere. However a skilled archer or marksman could easily defeat half or three quarters cover by not aiming at it. Sure, it's a harder shot, but he doesn't need to continue to shoot over and over and randomly get lucky to hit. The the AC modifier is not stupid, the d4 roll is.

    1. Agreed. AC measures how hard it is for an opponent to find an opportunity to strike at a vulnerable spot on the target: to grab an armoured foe and stab your dagger between two plates; to place yourself and time your axe strike to avoid your opponent's shield; to aim your arrow at the unprotected legs or neck of an enemy soldier. Cover is absolutely the same calculation.

      The system you're proposing is most reminiscent of the 1e DMG rule about helmets: a far too literal reading of the abstract nature of the to-hit roll, and one that doesn't make any sense of combat prowess (as measured by THAC0) as a set of strategic calculations.

    2. King, I assume that because that's how things work - you aim center of mass because that gives you the best chance of a hit. And you can't simply "defeat cover by aiming", that's absurd.

      You are arguing that it is not 4x harder to hit a square 1 foot on a side than one 2 feet on a side, and that is silly.

      Picador - AC is a problematic thing in D&D, as I've written about before. Your conception of it is incomplete and erroneous.

      I don't know the 1e DMG rule, but since it's in the 1e DMG, I assume it is a bizarre and useless rule. I do know that I am not using a "far too literal" reading of the abstract nature of the to-hit roll at all.

      This rule does, in fact, take into account combat prowess. Someone with a base CTH of 100% against an uncovered target has a 25% CTH against a target one quarter the size. Someone with a base CTH of 20% against an uncovered target has a 5% CTH against the 3/4 cover target.

      To argue that the higher-skilled marksman should have less than a 75% reduction is to argue that reducing a target's size makes it (relatively speaking) easier to hit (which is obvious bullshit).

      Where this rule falls down is with >100% base CTH rates, but I can live with that. I will edit the post to reflect that.

  4. The human body is not a circle, however, the place you hit is measured by a probability circle, so, as a consequence,if you have 90% chance to hit someone, if they have cover on their legs, your chance won't drop to 45%, since your probabilty circle still is hitting their body most of the time.

    Not to mention that AC is also movement(That's why Dex gives a bonus), so, it would at most work at 70% or less chance to hit(since Dex 0 is someone standing still and Dex 12 is an average for enemies).

    Finally, what about halflings? since they have 1/2 the human size, and, as such, 1/4 of the area, meaning 3/4 of their target area doesn't exist, and, as such, can't be hit.