Irgun’s reference is the Necromonger from the Chronicles of Riddick fictional universe

The Chronicles of Riddick is a 2004 American science fiction action film written and directed by David Twohy. It follows the adventures of Richard B. Riddick as he attempts to elude capture after the events depicted in the 2000 film Pitch Black.

The Necromongers are a religious empire that zealously and violently follows and propagates its religion Necroism. They are an absolute fanatic group that believes life is antagonistic to the natural state of the universe. They intend to convert or kill all who oppose them.

The Necromongers believe that each 'verse has its own god, that life is antagonistic to the natural order of the universe and must be purged from it to be reborn in the Underverse. The Underverse is their promised land, but they believe that unless a person dies "in due time,” they will not go to the Underverse. They also believe heavily in the philosophy of, "You keep what you kill,” believing that ending another person’s life entitles you to their property and position.

The Necromongers do not reproduce in order to avoid further propagating life, so all Necromongers are converts, not born into the religion. When someone undergoes the conversion, they receive the Mark of the Necromonger.