Crystal Ice Mirror

The user casts a spell that surrounds the target(s) with inescapable Crystal ice mirrors, on your turn you jump through the air jumping from mirror to mirror at insane speeds and throw deadly needles at the target(s) you roll a d20 for each target separately, the target(s) take piercing damage equal to the number on the dice. Each time you attack the target(s) must roll a 15 DC Dexterity saving throw, if they roll a natural 20 the Crystal Ice Mirrors will disappear and you will be knock you prone for 1 turn.

At spell slots level 6, 8, 10, you gain 1 d20 per attack.