While your Unholy Runes are both depleted, movement-impairing effects may not reduce you below 100% of normal movement speed.
Two days after giving us this talent they nerfed it to a 75% move speed. Even with this nerf i am very happy with where this talent puts us for mobility. Out running rogues, warriors, other dks and ret paladins makes this talent very useful. Our damage although nerfed too recently seems just fine for pvp and we should still hold our own in pvp. Just a little thought for the day.