Coocu wrote:
If you dont want to lvl up fire you could also lvl up first ice nuke to lvl 1, and do first lightning nuke + ice nuke + shock lion shout and then heaven lion shout when you get that skill

This is what I would do. You should get the 2nd book of ice nuke when you can, you only need lvl 1 of the first book to get it.
Though actually you should have lvl32 fire for the physical buffs if you use any weapon skills, and more importantly at higher lvl you can be status immune with fireshield+accessories. If you do this you could just get fire nuke lvl 1 it wont waste to much sp.