You actually can "have it all" and not break your agreement with Mordus.
-first, agree to let him teach you source skill.
-after, select you want to ask him more questions
-interrogate after why he possesed the dwarves
-that eventually will lead to you being able to inquire who his master is
-pick the option that says you will try to help him
-then pick the option to break his damn arm
mordus will TRY to tell you who his master is... but won't quite be able to.
there. now you have gotten your extra source point, did NOT break your agreement with Mordus, and Mordus dies about as horrifically as one could possibly die.
win/win/win
