## 2019-06-17

### Air Elemental Whirlwinds

Random math-y investigation: How powerful are air elemental whirlwinds? Pretty powerful. OD&D says this (Vol-2, p. 18):
Air Elementals: Air Elementals move only by flying, moving at a maximum rate of 36". When engaged in combat in the air they add +1 to damage scored from hits. They normally do one die roll of damage. They can turn into a whirlwind which will sweep all creatures under two hit dice away, the whirlwind being conical in shape, 3" diameter at the base, 6" diameter at the top, and as high as the number of hit dice possessed by the Elemental (16", 12" or 8"). Forming a whirlwind requires one full turn as does dissolving it.
A few other notes: The general elemental description on this page says, "Only magical weapons/ attacks affect Elementals", whereas OD&D Sup-I boosts that to, "Elementals are impervious to normal weapons and to magical weapons under +2" (p. 34). The "turn" in the last line is arguably the same as a "round" (or something), as they seem to be used interchangeably in this text, and the 1 turn = 10 minutes rule is not given until Vol-3 (e.g., the other elemental descriptions all say "move at a rate of 18" per turn" and the like). The AD&D Monster Manual limits the whirlwind to just 1 round duration, and adds a 2d8 damage factor to creatures it can't kill outright.

Consider using an air elemental against a large body of humanoids, such as in a mass-combat situation. If we use the by-the-book D&D scale that 1" = 10 feet, then the elemental can fly 360 feet in a round, and affect a 30' diameter along that path, for an area of about 10,800 square feet; if we allow one man per 5' square (25 sq. ft.), then that's about 432 men automatically destroyed per round by this rule. I'm pretty sure that makes the air elemental exponentially the most destructive mass-combat weapon in the game.

On the other hand, if we use the better-reasoned scale of 1" = 5 feet, then the distances are halved, and the area and number affected are thereby quartered: 180 feet move, 15' diameter path, 2700 square feet area, for about 108 men destroyed. I think it's then still the most destructive force against normal men, but not quite so stupendously overkill-y.

But there's a final limiting factor that's easy to forget; the rules for aerial movement in Vol-3, thought to be written by Dave Arneson, and inspired by "Dawn Patrol/Fight in the Skies" by Mike Carr. For air elementals (4th row down in the table on p. 26), the specifiers give "number of turns per move: 6", and "number of spaces between turns: 3". Given these and a hex map (specified in Vol-3 on the prior page), I attempted to find out what the most-compacting "sweeping" movement was that could be made by an air elemental in one round. Consider the following:

Path A: Trying to make the tightest loop possible; this depletes the available turns fairly quickly, and forces us to make a long straight path away from the fight at the end. Covers about 45 hexes in the initial loop, with a donut-hole in the middle.

Path B: Trying to make a back-and-forth sweeping action, but the required spaces-between-turns leaves sizable gaps between each "sweep". Each straight segment covers about 27 hexes. You need to have a packed-in army of about 30 rows x 15 columns (450 men) to hit a man on every hex of this path (for a total of about 100 victims, as noted above, assuming 1 hex = 1 man = 5 feet).

Path C: Here I have the elemental spin away and then back, so as to sweep a kind of contiguous block at the start and end of the path. The top-left part thereby has something approximating a 6 x 8 rectangle, thereby hitting about 48 normal men in close formation there.

Path D: An iteration on the previous strategy; again, we get a top-left block of about 6 x 8 = 48 contiguous hexes.

Conclusion: In open mass combat, I might summarize this with a rule saying that an air elemental in whirlwind form can wipe out about 50 normal men in formation in one turn. That's still very powerful, so before one shows up in your game you might want to consider interpreting or house-ruling things to a power level that you're comfortable with. For example, reducing the diameter of the whirlwind (AD&D took it from 3" to 2"), making the attack 1d6 damage or with a saving throw, etc. Another option is to strictly enforce the book's given rule, "Forming a whirlwind requires one full turn as does dissolving it", which would arguably make it still extremely powerful in (turn-based) mass combat, but basically not ever usable in standard man-to-man D&D action. Thoughts?

1. Details of the elemental's capabilities while forming/dissolving a whirlwind are notably lacking. If it takes 10 minutes to form, that's a long time for the elemental to be concentrating, or whatever. But I kind of like the thought of that. If there are heroes about capable of harming the elemental, it can't spend 10 minutes to summon up a whirlwind. But if there are only ordinary humans (et al) about, then it can work itself up into a big wind and go to town.

I'm not sure about equating "swept away" with killed outright although it's not unreasonable. Might be better to rule "swept away" as "blown randomly away and takes damage as in an attack" which would kill many but not all contacted. In a mass combat situation though, I'd say any unit contacted by a whirlwind would be effectively destroyed -- maybe not all dead, but certainly combat-ineffective going forward.

1. Yeah, my instinct would be that the whirlwind feature should be an interesting gag that PCs confront. I wouldn't want to rule that you just never see it against high-level PCs. But if the formation time was 2 or 3 rounds I wouldn't mind that at all.

The AD&D MM does explicate "sweeps away and kills all creatures under three hit dice", so I assume that was Gygax's intent in OD&D. But interpreting it otherwise would be one of my favorite takes on it (not that, say, 1s6 damage would be much different against normal soldiers).

2. Do you interpret "sweep away" as "kill", or is it stated anywhere in the rules?

1. Oh, I was beated to it.

2. In the AD&D MM, yes (see above).