Cardice Oil

When poured over water, oil pools on surface &
takes 1 round to spread from point of origin
(20foot radius). End of round, cardice oil flash-freezes surface of water, creating ice sheet over affected area. Ice can support 200 pounds of
weight. Weight in excess causes sheet to crack &
break. Ice sheet becomes unstable & breaks up on
its own after 1 hour, or 20 minutes in hot climate. Creatures whose bare skin contacts cardice oil
takes 1d6 of nonlethal damage each round,
the oil is ineffective as