Mab smiles a little and touches the air around Clara's hand without actually touching her, it might be a little too much for the ghost to have a fae actually touch her. "With your word, so mote it be." She can't say Clara won't regret it. She very well might. But There are also advantages to getting on a fae's good side. Clara now has access to significant power that can affect the world in more concrete ways that she can herself. "I have every confidence in you."