As was shown, the Goblins were unaffected by the anti-magic zone and were a force to be reckoned with. The cultists might have had the upper hand initially in their attack, taking the Goblins by surprise, but the cannon and expertise both King Fradlok and Filknas employed showed that the cultists were not prepared to fight beings who don’t have magic. They knew how to deal with Inferi and were effective in it. The scene of them cutting up the giant Inferi amalgamation came to mind. 