As a full-round action that does not provoke attacks of opportunity, a ningen can rapidly submerge itself beneath the water and then launch itself upward to break the surface and crash down. The impact produces flying chunks of ice dealing 10d6 points of cold damage and 10d6 points of piercing damage to all creatures and objects within a 30-foot radius. Creatures that take cold damage are staggered and entangled for a number of rounds equal to the ningen's Hit Dice, and those that take piercing damage are sickened for the same number of rounds. A successful DC 27 Reflex save halves this damage and negates the staggered effect. The save DC is Constitution-based.