The rulebook says "Some artifacts, covenants, or curses have a limited number of times you can use them. When these come to an end, you must discard them immediately. Once such an artifact, covenant, or curse is activated, it must be counted as having been used. This is true even if other events duplicate the effect of the artifac, covenant, or curse during the turn. "
I agree with Guardian. This card has ongoing abilities, so can't be discarded until they are complete. At that point, you immediately discard it.
Mike
