+6 to any of fireball/lightning/ench and 20fc and 2 sox

would that be good without the respective mastery?

just wondering if cubing demon hearts or dimensional shards with 3 chippies is worth it, because there you can't possibly roll mastery

Masteries (specially lightning) are going to end with around +500 damage, not adding 3 extra levels on that is not the end of the world, more points in the spell you are using is a lot more important.