Choose a creature within range,The creature must make a con save or take 2d6 radiant damage.In addition,for the rest of the duration the target takes another 2d6 radiant damage at the start of their turn.During this time,whenever they would heal they would instead,Take radiant damage equal to the amount of hit points they would heal.

at higher levels 

When cast with a spell slot of 4th level or higher,The damage dealt by the spell increases by a d6 every level above 4th.