Success,  as the cleric comes through with a bit of commonsense with his wisdom.    The black mold can be destroyed one of two ways.   One is through quick and most efficient way of fire.   He would have been exposing himself to dangerous toxin poisons.   And even if he does the rock idea.  It will cause perhaps the cloud to erupt. But the mold will still be there.<br/><br/>But wait,  another way is to dry out the room.   This process through takes twenty four hours.  But how could they do that.  How could they do it.  Did he have a spell or perhaps one of the others.  That would change the climate of the room from the damp to a dry humid one.   That would naturally kill the mold in the process of 24 hours.