Burden

Target a creature in range wearing armour; they must make a dexterity saving throw or your magic strikes their armour, making it become heavy, cumbersome, and awkward. Creatures wearing magical armour have advantage on the save as the armour may resist the effect. 

While you concentrate on the spell the creature does not have proficiency with the armour they are wearing, and so has disadvantage on any ability check, saving throw, or attack roll that involves Strength or Dexterity, and can’t cast spells. Removing burdensome armour is possible but takes twice as long as usual. 

Creatures with a strength score of 19 or higher may equip, wear, or remove burdensome amrour without penalty.