Eternal Frost

You take the powder and throw it into the air whilst reconstructing it into a blizzard storm. The storm reaches a 10 feet radius around you and stays in place after cast. All enemy creatures inside the radius take 6d6 cold dmg every round. The creatures also gain a stack of frost, when 4 stacks are gained the creature gets frozen *(petrified) until thawed or the spell ends. 

At higher levels: At 9th level 7d6 dmg and only 3 frost stacks required.