Burden of Time

When you cast this spell, you may curse someone with the burdens of time; they must succeed on an Intelligence saving throw or take 1d4 necrotic damage and have their base speed reduced by half until the end of their next turn. 

This spell's damage increases by 1d4 when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).