Any caster brave enough to cast a knock spell on a chained angel can remove the creature’s shackles, but this always exposes the caster to a blast of unholy flame as a reaction. The caster takes 16 (3d10) fire damage and 16 (3d10) radiant damage, or half as much with a successful DC 16 Dexterity saving throw. If the caster survives, the angel makes an immediate DC 20 Wisdom saving throw; if it succeeds, the angel’s chains fall away and it is restored to its senses and to a Good alignment. If the saving throw fails, any further attempts to cast knock on the angel’s chains fail automatically for one week.