Xandorz just did an amazing job breaking it down. I just felt I should mention why, I believe, Mage is better PVE and the Lock for PvP. I believe his reasoning was that in pve 2 sheeps is much better then 2 fears. But in pvp fear is much better for casters. He can correct me if I am wrong, or had a better reasons then described below.

I will ask how would the lock or Pala break frostbite?