My final build:
Main character: magician type....put mp regeneration, quick feet, arcane tap, scorch +, boulder, and normal heal on. For gears, I put on HP and MP raising gears, and then put on that elemental mastery weapon.
Mark: I build him as wall with toxic cloud ability with poisonous claw attack.....
Rok: my favorite, I build him with quick feet and evasion, and then equip him with rabid bite...
Bane: put on icycle + and spark on.....he is my opposite in term of elemental attack...
Lilith: I build her as healer and debuffer....heal+, cure+, and debuffing magic....