Whirlwind

Some creatures can transform themselves into whirlwinds and remain in that form for up to 1 round for every 2 HD they have. A creature in whirlwind form cannot make its normal attacks and does not threaten the area around it. Creatures caught in the whirlwind take a –4 penalty to Dexterity and a –2 penalty on attack rolls and must succeed on a concentration check (DC 15 + spell level) to cast a spell. An affected creature must succeed on a Reflex save (DC 10 + half monster's HD + the monster's Strength modifier) each round or take damage as if it were hit by the whirlwind creature's slam attack.