Odd thing, but as I'm vetting the Chimera 2.1 update, I started questioning area-of-effect (AoE) attacks. In my experience, the conventional wisdom for AoE has always stated that all targets within the blast radius take damage. Pretty straight forward, and you may be asking what could possibly be unclear about that.
Well, it's this: does area-of-effect damage apply to each target in a blast radius, or each occupied space in the blast radius?
This is an esoteric distinction, one that only manifests when you use miniatures on a gridded battlemat. But since that's a pretty common convention, I strongly suspect this has been debated before. Only, I don't know who won, and I couldn't find anything in my three-and-a-half-minute search of the Interwebs. Consequently, I'm opening up the issue for a fresh evaluation. While I have my own thoughts on the matter (of course you do, I hear you saying to yourself), I want to hear others weigh in on the topic.
Area of Effect Basics
Let's start with a gridded battlemat. The scale doesn't really matter—just assume that each square on the grid contains no more than one combatant. Some combatants, like dragons or horses or tanks, are big enough to take up more space—let's say two squares or more. Let's also introduce a straight-forward area-of-effect weapon, a grenade that does 1d6 points of damage with a blast radius of 1 square. This means that the blast radius includes about nine squares on the battlemat—the target square (ground zero) plus one additional square in every direction. When the grenade goes off, anything in one of those nine squares gets hit for 1d6 points.
This is shown in the illustration above-right. The red square is ground zero and the red circle is the area-of-effect. There are two Defence Robots within the grenade's blast radius, so each takes 1d6 points of damage.
Similarly, the second illustration (at right) shows a tank caught in the grenade's blast radius. Again, the red square is ground zero and the red circle marks the total area-of-effect. Note that the tank takes up two squares. However, it's still inside the blast radius (or, more accurately, part of it occupies the area-of-effect), so it also takes 1d6 points of damage.
These examples are straight-forward. In the first, you have multiple targets damaged because each occupies a square inside the blast radius. In the second, you have a single target that's damaged because it, too, occupies a square inside the blast radius. Simple.
But now I'm about to blow your mind.
Single Target or Single Blast?
What if a single target takes up multiple squares inside the blast radius? Does it take one die of damage because it's a single target, or does it take one die of damage for each square within a single blast radius?
Consider the examples above. When the robots are damaged, it's because each is within the blast radius. Same with the tank—it's also within the blast radius. The implication in both examples is that damage applies to each square within the area-of-effect. As a result, each robot gets 1d6 points of damage, as does the tank.
But what if the whole tank was inside the blast radius? As in, both squares occupied by the tank are inside the grenade's area-of-effect?
This is shown at right. As before, the red square is ground zero and the red circle is the blast radius. But this time, the entire tank is in the blast radius. So the question is, when it's hit by the grenade, does it take 1d6 (single target) or 2d6 (single blast) points of damage? Here are the approaches I've come up with:
Single Target Argument
Mechanic: Each target within the area-of-effect takes damage from the attack
Interpretation: If a target, or part of a target, is within the area-of-effect, it takes one die of damage
Rationale: Big targets resist damage better than small ones; plus, the damaged part of a large target may shield other parts from the blast
Single Blast Argument
Mechanic: Each square within the area-of-effect is subject to attack damage
Interpretation: A target takes one die of damage for each square it occupies within the blast radius
Rationale: Big targets risk greater exposure to the blast; plus, this is consistent with the apply-damage-to-each-square approach you'd use for smaller targets (like the robots, above)
And the Verdict Is...
I can appreciate the rationale for each approach, though the voice in my head keeps pitching the Single Blast Argument. After all, if there were a Defence Robot in each of the blast radius' nine squares, each robot would take damage, and that suggests that damage is applied to every square in the area-of-effect. That's a strong precedent against the single-target stance.
But, given a sufficiently logical and well-articulated appeal, I'm willing to be swayed. Broadly speaking, I have only two requirements: (1) whichever approach is used, it has to work in all situations—the last thing I want is a conditional mechanic for what should be a straight-forward ruling, and (2) the approach can't bog down play, and that includes taking time-outs to provide a lengthy explanation of why the approach I chose was chosen (that said, I'm all for providing short explanations that deliver iron clad justification in two sentences or less to keep the game moving).
So...what's your take? Do either of these arguments pass the sniff test better than the other? How do/would you handle this issue in your game? Is there a third mystery option my enfeebled brain has overlooked? Do you think grenades could even scratch a Defence 'bot?
Let me know. When I reach a decision—based on your input—I'll post a follow-up and put it in the Chimera 2.1 revision that's due out in a few weeks.