Yamu's Icebind

You choose one creature that you can see within range and command the weave to turn into an icesheet that lays itself upon the target.

The target must make a Constitution Saving Throw. On a fail, it takes 2d8 cold damage and its speed is reduced by a number of feet equal to 5 times your proficiency bonus for a minute. The target can also not use the dash or disengage actions while its speed is reduced this way.

On a successful save, the target only takes half damage and its speed is not reduced.