Isen Server is based on Crafted gear (Weapons, Armors, Accs) where the base stats are inflated (Str, Dex, Agi, etc) vs Jainus that is what the game was meant to be crafting, forging, etc.
There are classes that benefit more out of their main stat than others when using some skills.


Priests Judgement skill deals 10 times Psy and Int stats + Magic atk damage to targets (9 because server said so) around them in a 20 meters distance. 3 seconds cooldown.

Wizzards Ring Burst skill deals 9 times Psy stats + Magic atk damage to targets around them in a 20 meters distance. 4 seconds cooldown.



This both skills are a copy paste of each others with minor differences that just makes Priests deal more burst damage in 3 seconds than wizzard does in 4.
An Isen Priest is more powerfull damage dealing wise than a Jainus Priest both in end game gear. Has more Int and Psy with crafted gear than Forged gear.

Now the Jainus Priest has more survivability than the Isen Priest because of the Upgraded weapon 130% HP boost. Has higher inflated stats with Forged gear than crafted gear.

Pure atk is another factor that if I was to put here the explanation would be too long and boring.



Thats the diference when it comes to Jainus vs Isen servers.