Blade of Agathys

Spectral frost spreads across the surface and enhances one melee weapon of your choice. Every time you make a melee weapon attack with that weapon for the next minute, the frost does extra damage to the target of the attack equal to your spellcasting ability modifier.

    This spell's damage increases when you reach certain levels. The bonus cold damage increases by 1d4 at 5th level (1d4 + spellcasting ability modifier), 11th level (2d4 + spellcasting ability modifier) and 17th level (3d4 + spellcasting ability modifier).