Until the PCs defeat the creatures, they suffer a -4 penalty to attacks and saving throws. In order to stand, a PC must roll under half his or her Constitution score. Alternately, a PC may elect to attack while prone, suffering an additional -2 penalty to attack and allowing the creature a +4 to attack.
Their cold touch drains one point of Constitution each time they hit with a claw attack. The effect lasts one turn per successful claw hit, assuming that measures are taken to warm the affected victim. If the victim's Constitution reaches zero, he falls unconscious for a turn and awakes weak and unable to move until his Constitution reaches half of its original score. At that point, the victim can begin to move around again.