While I was working on my MobArena, Khobbits joined and then made himself moderator when he wasn't supposed to be moderator (He never had op)! So I tried to ban his ip, but it didn't work, so I banned his name and then he left. After a few minutes, KHobbits unbanned himself and joined the server again! I eventually realised that he had asisstant called ElgarL (who was also not supposed to be moderator) who unbanned KHobbits everytime I banned KHobbits. KHobbits told me that if I banned him again he would crash my server. Quickly, I banned KHobbits, ElgarL and both of their ips. I found out that KHobbits was the author of Essentials, and I thought he put some code in the Essentials so he could make himself moderator and unban them selves.