Synaptic Strike

As part of the action to cast this spell, you must make a weapon attack against a creature within the spell’s range, otherwise the spell fails. Your weapon becomes capable of influencing the enemies mind. On a hit, the target suffers the attack's normal effects, and it becomes sheathed in translucent chains only the target and caster can see until the start of your next turn. If the target willingly attacks anyone other than you before then, it immediately takes 1d8 psychic damage, and the spell ends.  

 This spell’s damage increases at higher levels. At 5th level your melee attack deals an additional 1d8 psychic damage, and the secondary damage also increases to 2d8. Both damage rolls increase by 1d8 when you reach 11th and 17th levels.