Thunder Strike

The first time you hit a creature with a melee weapon attack during this spell’s duration, your weapon hits the target with a deafening sound that is audible only to the target and the attack deals an extra 2d8 thunder damage to the target. Additionally, the target must succeed on a Constitution saving throw or be deafened until the spell ends and if the creature is huge or smaller it also falls prone.   

A creature deafened by this spell makes another Constitution saving throw at the end of each of its turns. On a successful save, it is no longer deafened and the spell ends. A creature made of inorganic material such as stone, crystal, or metal has disadvantage on this saving throw. A non magical object that isn’t being worn or carried also takes the damage from this spell.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the extra damage increases by 1d8 for each slot level above 2nd.