Looking at the Chuspiki here: http://www.d20pfsrd.com/bestiary/monster-listings/magical-beasts/chuspiki
It seems almost certain to me that its Air Blast ability will eventually be explicitly limited to 3HD, given that the Silvanshee Agathion's lay on hands ability was revised to limit itself to 2HD and it was just 1/day, while air blast is at will.
But for now, other than that one precedent, is there any RAW or FAQ to support such a limitation?
