What kind of action must an Air Elemental take to become a whirlwind?
How often can an Air Elemental use Whirlwind?
The ability's template includes a frequency
whirlwind (3/day, 10–30 ft. high, 1d6+6 damage, DC 15)
But the bestiary entry for Small Air Elemental doesn't.
whirlwind (DC 12, 10-20 ft.)
If a Small Air Elemental creates a 20' tall whirlwind, what's the size category of the whirlwind?
Creatures one or more size categories smaller than the whirlwind might take damage when caught in the whirlwind [...]
Is it the size of the creature in its normal form (Small Air Elemental affects Tiny creatures), or does it go by the height of the whirlwind (≥10' affects Medium creatures, ≥20' affects Large creatures, etc)?
- The special attack whirlwind is a supernatural ability and, as a supernatural ability with an unstated activation time, it takes a standard action to activate.
- According to the whirlwind ability and the description of the Small air elemental, a Small air elemental can remain a whirlwind for 1 round after which it resumes its original form. It can then take a standard action to once again assume whirlwind form. It can do this any number of times per day (which, given the ability's limited duration, isn't usually a big deal).
- A Small air elemental can create a whirlwind with a height between 10 ft. and 20 ft. According to this chart a whirlwind with a height of 10 ft. to 15 ft. is Large, and a whirlwind with a height of 20 ft. is Huge. The size categories of affected creatures are determined by the whirlwind's size category not the size category of the creature making the whirlwind (i.e. "Creatures one or more size categories smaller than the whirlwind...").
Supernatural abilities take a standard action to activate. This is referenced on the following chart, under Standard actions:
Size, Reach, and Threatened area:
A whirlwind 10-30 feet tall can be treated as a Large, or a Huge Whirlwind, depending on the elemental. The special attack text for whirlwind states the following:
The whirlwind is always 5 feet wide at its base, but its height and width at the top vary from creature to creature (minimum 10 feet high). A whirlwind’s width at its peak is always equal to half of its height. The creature controls the exact height, but it must be at least 10 feet high.
An Air elemental can use a whirlwind for up to 1 round for every 2 HD they have. If the creature has a fly speed, it can continue to fly at that same speed while in whirlwind form; otherwise it gains a fly speed equal to its base land speed (average maneuverability) while in whirlwind form.
Which is located here: