Ethereal Shackles

Choose a spellcaster that you can see within range. The target must succeed on a saving throw for its primary spellcasting statistic, or it's arcane presence within the Ethereal Plane is restricted, causing it to be unable to cast spells of any kind. At the end of each of its turns, the target can make another saving throw. On a success, the spell ends on the target. 

At Higher Levels. When you cast this spell using a spell slot of second level or higher, you can target one additional spellcaster for each slot above 1st.