Does Ice Strike replace Lightning Bolt ?
Definately, the range is superior to Lightning Bolt in addition that it freezes the monsters, does more damage, and is ice elemental. I consider ice elemental already a good enough advantage. You can even completely skip the Lightning Bolt skill in 2nd job if you like, since it becomes quite useless later on; but it would mean more difficult for you to train (however some ice mages only train on fire boar & fire drakes, so it won’t be much of a problem).
