Sylvain's Seething Spirit

You summon a hellish spirit of pure anger and fury to possess a creature anywhere within 60 ft of you that you can see. The spirit then attempts to possess the target, forcing them to make a Charisma saving throw, which they can choose to fail. On a success, the spirit is dispelled back into hell.

On a failure, the target gains a bunch of different effects. They have resistance to nonmagical bludgeoning, piercing, and slashing damage, their speed increases by 10 ft, and they deal an extra d6 of their weapons damage type. On the downside of that, they are so blinded by rage that they can only use their action to attack and they can't gather the focus to cast spells.