We installed a system called specialty classes system. This means each class has bonus damage against 1 other class.
This way all classes are useful in-game and good for bigger events like SIEGE & BIG BOSSES
Before we installed this system we made sure all classes have +- the same damage and defense against each other and on top of this we installed the new system.
Mu online bonus powers par class
Dark Wizard power bonus vs Slayer
Blade knight power bonus vs Summoner
Elf bonus power bonus vs dark knight
Magic gladiator power bonus vs dark lord
Darklord power bonus vs Dark wizard
Summoner power bonus vs Grow lancer
Ragefighte power bonus vs ELF
Grow Lancer power bonus vs Rune wizard
Rune wizard power bonus vs Rage fighter
Slayer power bonus vs Magic gladiator
PVM system is around the same damage/defense for each class. We based this on kill time of strong monsters.