Deals on-going cold damage to the target every 2 seconds for 12 seconds. The damage starts small, and grows larger as the spell continues. Each phase lasts 4 seconds.

First phase: 1d4 damage +2 per 3 caster levels (max +12 at caster level 18).
Second phase: 2d4 damage +4 per 3 caster levels (max +24 at caster level 18).
Third Phase: 3d4 damage +6 per 3 caster levels (max +36 at caster level 18).