Adir's Absolute Zero ( do not use)

You create three glowing daggers of magical snow. Each dagger strikes a creature of your choice that you can see within range. A ball deals 1d8 + int mod cold damage to its target. The darts all strike simultaneously, and you can direct them to hit one creature or several. the third dagger leaves the target freezing cold and gives them vulnerability to cold damage for one minute on con save equal to your spell save dc

Using a Higher-Level Spell Slot. The spell creates one more dagger for each spell slot level above 4th.