Thundering Scourge

When you invoke this spell a whip of crackling magical force materializes in your hand. When you first cast the spell, and as an action thereafter, you may make a melee spell attack against a creature within 15 feet of you. On a hit, that creature takes 4d4 thunder damage and must make a Constitution saving throw or be deafened until the beginning of your next turn.

While deafened in this way, a creature has their movement speed reduced by 10 feet. When you hit with this weapon, a crack of thunder detonates, audible out to 300 feet. 

At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the number of attacks you can make with this whip increases by one for every two slots over 1st.