u should increase all fire and ice skills and ofcourse all passive skills
from earth skills (earth shock,earth barrier,earth quake,earth fence)
from lighting skills(lighting shock,teleport,lighting impact,aerial teleport)
some ppl well say that charged wind is useful espicially when defending a cleric but in my opinion how come it is useful while u can kill a mob in one hit or 2 maximum........there is also charged squall very useful but at lvl 80 so when u get to lvl 80 start increasing the first lighting skill to get this one.
this is the best thing to do in my opinion :D :D
:D