Typically, we advise you make a log for participation of others, either planned or open to all comers, and do it howsoever you want. Your method of him hearing about this is perfectly sensible. Once you require our attention to adjudicate your efforts, simply reply here and we will let you know how it goes.

For purely hypothetical example: you might attempt to slay the exorcist, then put his head on a pike. Nothing warns people off like a head on a pike! Once you've set the scene, you need merely ask us and we will determine your success of failure -- typically, through random roll, with a bonus or penalty based on your actions in the scene.