Is there any item in Mu Online Season 9 or below that nullifies Stun?

I play a Mu Online server season 9, where there is "stun" such as the one done by BMs usage of mace and the skill Death Stab.

Recently I and a couple of friends noticed that a player of the rival ally was almost not affected by Stun, treating it in the same form as with ice plus Antidote: as soon he got stunned, instead of being affected for the traditional 2 seconds, he immediately manages to get out of Stun.

This seems to either suggest some hack device is being used or he managed to find out something inside the game that works for Stun like the Antidote works for ice. If the second is the case, I would like to know that it is.