You target a point within range. That point becomes the top center of a cylinder 10 feet in radius and 40 feet deep. All ice inside that area melts immediately. The uppermost layer of ice seems to remain intact and sturdy, but it covers a 40-foot-deep pit filled with ice water. A successful Wisdom (Survival) check or passive Perception check against your spell save DC notices the thin ice. If a creature weighing more than 20 pounds (or a greater weight specified by you when casting the spell) treads over the cylinder or is already standing on it, the ice gives way. Unless the creature makes a successful Dexterity saving throw, it falls into the icy water, taking 2d6 cold damage plus whatever other problems are caused by water, by armor, or by being drenched in a freezing environment. The water gradually refreezes normally.