Runes of Magic US / AU

So once again we were doing Sismond and the fight was going fine until a Stone spawns in the damn coffin again. These stones can't be hit by single target skills and can only be damaged by aoes or aa'ing if in range. This is not a "challenge" for the fight, it's a horrible boss mechanic that needs to be fixed as it has a big chance of wiping the party; wasting time and resources. These stones can spawn outside of the walls too, making them unreachable and wiping the party. Sorry for double post but this needs fixing as it's just basically entering the fight knowing that there's a somewhat high chance we will wipe due to stupid and unnecessary reasons.