Dsvar's Phantom Itch

1 target makes a Wis save against your Spell Save DC. On a fail, they start itching at their skin and can only take the Itch action. The Itch action allows makes them take 1d4 slashing damage. (They do not get an additional save upon taking this damage) They keep all of their movement speed. On a success, they are not affected. They can repeat the saving throw at the end of each of their turns. They roll an additional save every time they take damage.