Secondary skills in Heroes 3.

water magic isn't really needed, well unless it's to remove enchantments, clone, and sometimes teleportation works...
movement on water is rarely needed...
fire magic has good attacking spells, air magic will be useful with haste, fly and dimensional gate, and earth - with slow and town portal...
well and of course some other spells

what is attacking fire magic? Inferno (or something even stronger)? or Armageddon which kills everyone? =))) I'm not even talking about the fire and ice balls :D

now earth has a level 5 spell, I don't remember what it's called, there's like a cauldron drawn... disintegration(imposoliy) maybe... in general a powerful thing...
air has lightning and chain lightning...