A square metal gizmo with buttons all over it. Can be placed on the ground or on a person using a slight of hands check. When activated emits a field in a 30 degree radius. Any spellcasting class within the radius must make a wisdom saving throw at the start of their turn with a save DC of 17. On a failed save, any spells tried to cast that turn will be at disadvantage and will have their effect halved. On a successful save, they will face disadvantage while casting. 

If a caster fails a save 3 times in a row while inside the circle's effect, they will be unable to cast spells for 3 turns. 

Notes: By a spellcasting class