Colonic Transformation

You transform up to ten creatures of your choice that you can see within range into a steaming pile of excrement. An unwilling target must succeed on a Wisdom saving throw to resist the transformation. An unwilling shapechanger automatically succeeds on the save.  If you concentrate on this spell for the full duration, the transformation becomes permanent.

On a successful save, the target is not transformed but is assailed with a horrid, blinding stench for the duration and automatically fails any ability check requiring sight. Attack rolls against such creatures are made with advantage and its attack rolls have disadvantage.