Crystallize

This spell turns 1 cubic foot of water per level of the caster into ice, or forms a 1 -inch thick layer of ice over an existing pool of water. Many of the people and creatures of Athas have never seen ice, and may consider it a treasure, even if told it will last only for a short time. Of course, the priest doesn't have to tell them the ice will melt. Anyone walking on a patch of ice must make a successful saving throw vs. paralyzation to remain standing. If failed, the individual falls and spends the rest of the round trying to stand up.