The Lodestone Marauder was one of the guardians that tried to protect a spirit shackle. His magnetism was kinda useless against the heroes because no one was attracted to it. I mean, everyone made their saves and could quickly dispatch it.
The Lodestone Marauder would have the ability to pull the weapons of the heroes to himself, disarming them, but it didn't work. Even with his increased Armor class against metal weapons it was no match against the heroes, who walled the other combatant (a flesh golem) in.