Thunder Dome

You surround yourself with 3 crackling energy orb, when you are hit by melee attack and have at least one orb remaining the attacker must make a constitution saving throw against your spell save DC, and take 4d6 thunder damage and is knocked prone, on a success the target takes half damage and isn´t knocked prone.

When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 for every slot levels above the 4th.