The ghost has made no overt offensive moves attack the group, though his desires should now be more clear. Anyone is free to examine the door. It is protected by a spell and also by a complicated series of ancient devices - not at first identifiable as locks. There are Tevinter runes around the outer edge of the doorway - which Caius is most likely able to read. They state that the door was "bound by blood and by blood undone". If anyone were to reach out and touch it they would be shocked rather badly by the spell over it.