Enialeigh's Glacial Spear (Arteria)

Cold air consolidates in your hands, forming a spear of pure ice. This magic spear lasts until the spell ends. It counts as a simple melee weapon which which you are proficient. It deals 3d6 cold damage on a hit and has the finesse, versatile (3d8), and thrown properties (range 20/60). In addition, when you hit a creature with an attack, their speed reduces by 10 feet until the end of your next turn.

If you throw the spear, it detonates on impact. Each creature within 20 feet of the point where the spear exploded must make a Dexterity saving throw or take 4d6 cold damage, and this spell ends.

At Higher Levels. The damage from the spear throw increases by 16 die for each spell slot level above 4.