Wither

Choose a creature that you can see within range. The target must succeed on a Constitution saving throw or is slowed, like in the spell "Slow" for the duration and suffers 3d6 force damage at the start of its turn. The damage increases every other turn by 1d6 until the spells ends. At the end of each of its turns, the target can make another Constitution saving throw. On a success, the spell ends on the target.

At Higher Levels. When you cast this spell using a spell slot of 6rd level or higher, you can target additionally another creature in range.