Brutal Blade

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a critical hit, the target suffers additional damage equal to your spellcasting ability modifier.

This spell’s damage increases when you reach certain levels. At 5th level, the melee attack deals additional 2d8 + your spellcasting ability modifier on a critical hit. The damage roll increases by 1d8 at 11th level (3d8) and 17th level (4d8).