Cryobomb

A glowing bead of ice forms from your finger and shoots out to a point within range, where it remains and grows colder for the duration. When the spell ends, either because your concentration is broken or because you decide to end it on your turn, the bead breaks apart and lets out an ice storm that flash freezes anything near it and spreads around corners. Each creature within a 20-foot radius sphere centered on the point must succeed a Constitution saving throw. A creature takes cold damage equal to the accumulated damage and is paralyzed for a number of rounds equal to the accumulated number on a failed save. If a creature succeeds the save, it takes half as much damage and is not paralyzed. A creature can remake the Constitution saving throw at the end of each of its subsequent turns in order to end the paralysis.

This spell's base damage is 8d6 and its base paralysis time is 1 round. If at the end of your turn the bead has not yet detonated, the damage increases by 1d6 and the paralysis increases by 1 round.

If the glowing bead is touched before the interval has expired, the creature touching it must make a Dexterity saving throw. On a failed save, the spell ends immediately, causing the bead to explode in a freezing storm of ice. On a successful save, the creature can throw the bead up to 40 feet. When it strikes a creature or a solid object, the spell ends, and the bead explodes. The cold freezes objects in the area and puts out nonmagical flames.