Astral Barrage

You create a portal to the cosmos and send asteroids
hurtling through it. A creature of your choice that you
can see within range must succeed on a Dexterity
saving throw or take 7d6 bludgeoning damage. You can
use an action on subsequent turns to keep the portal
open and target another creature, which must make
the same saving throw. The spell ends if you use your
action to do anything else. While concentrating on this
spell, your speed becomes 0.

At Higher Levels. When you cast this spell using a
spell slot of 4th level or higher, larger asteroids fly
through the portal and the damage increases by 2d6
for each slot level above 3rd.