make a new buff -> something like this:
Magical defence 17% reduce.
Physical defence 17% reduce.
Magical attack power 27 increase.
Physical attack power 27 increase
the higher the skill the more mag/phy attack power you gain but lose mag/phy defence or hp or mp etc... make it so everyone needs to buff it with shield and just add this skill in heuksal/bicheon/pacheon so everyone can use it... dont know if it's possible but just an wild idea ;p