Delayed Chromatic Blast

You hurl a 3 inch diameter sphere at a space of your choice
within range, imbued with either acid, cold, fire, lightning,
poison or thunder energy. It explodes into a 10 foot radius
sphere around the point at the start of your next turn. Anyone
within the sphere must make a Dexterity Saving Throw or
take 4d8 damage of the type you choose, and half as much
damage on a successful save.
When you cast this spell using a spell slot of 2nd level or
higher, the damage increases by 1d8 for each slot level above
1st.