I take it the dead adventurers were low leveled people and became those Kallaps [thus low leveled, you can see the cleric Kallap uses a level 8 mace, archer Kallap uses a level 8 bow, mage Kallap uses a level 15 staff, though the fighter Kallap uses something unusual which looks like a Katana], powered by Helga himself to become his own minions... ???
-imagination-