Torturous pain

You touch the a single target that is within your reach. If the target is a creature, it feels a shock of severe pain.
If you cast this spell on the same target every round the pain becomes continues and grows even more painful for each passing minute.
A creature that has been under this spell's effect for longer than a minute must make a constitution save against your spell save DC, becoming stunned from the amount of pain on a failed saving throw but stopping the pain altogether on a successful one.
A creature stunned by this spell can reroll the saving throw once every minute, freeing itself from the effect on a successful save. Additionally, if you ever stop casting the spell on a creature that you have stunned with it, that creature is automatically freed from the spell's effects the next round.