Dark Urge

One terrifying night, you woke up not in your bed, but near a dead body. Your dominant arm ached from stabbing something over and over, and now you find yourself inescapably drawn towards unimaginable cruelties. Where do these thoughts come from?

When you succumb to your urge, you can't control your body anymore and the Dark Urge controls you. Any creature - including allies, 25 feet near you must make a Wisdom save with a DC of 14, or be frightened of you until the Urge subsides. The Dark Urge lasts for 10 rounds, and can use it to a number of your Constitution score willingly.

If you take the Attack action with a light weapon, you can use a bonus action to attack again. Using light weapons during this possession will give you advantage, and using non-light weapons will give you disadvantage. You gain +10 walking speed during this, capping at 40 feet, and you gain expertise in the Intimidation skill during the possession.

If you aren't in combat, the Urge can tell you to do something that would be incredibly cruel. You must make a Wisdom save with a DC of 14. On a failed save, you failed resisting it, and do whatever you were told. On success, you resist it.