Using cold to directly harm your enemies is one thing. You can also turn it to your advantage by using cold against water, freezing the area around you.

Encounter   ✦     Arcane, Elemental
Standard Action      Area burst 3 within 10 squares

Effect: You cause nonliving water in the burst to freeze to a depth of 6 inches. Mud or swamp freezes, becoming normal terrain. Wet floors change to slick ice, becoming difficult terrain. Ice covers bodies of water in the area, which can now be walked on (although the ice is difficult terrain). A creature that enters a square of this ice or starts its turn there must make a DC 11 Acrobatics check or fall prone. The transformed ice remains frozen until it melts naturally.

Published in Heroes of the Elemental Chaos, page(s) 93.