[ivra]

I tend to do the following when playing the three classes:

Warrior:
I use the pet dragon to deal damage. You can easily get 100+ and even close to 200 Rage. That means that maxed Fiery Phantoms, Lava Call and Dragon Dive can be used to deal massive damage to enemies. Ball of Lightning is very useful for a warrior as well, but I think this one is especially useful when you play as a mage. As a warrior I use my spells mostly for control and to cast Phantom. Since your leadership is high your phantomed stack becomes large even if your int is low. Against normal units it is very effective to cast phantom on units that summons new creatures. These summoned creatures do not vanish when the Phantom spell expires. Royal Griffins are very potent in this situation since you can get three cannon-fodder units more or less in the face of the enemy. It is very likely that the enemy attacks them instead of your main units.

Mage:
As a mage I tend to use my spell book to do most of the damage. I focus on a high int and use my pet dragon mostly for digging and mana. The only damage dealing ability I max is the Ball of Lightning. Since I fight using my spell book, I tend to only use Phantom when the battle is over to resurrect my fallen troops, by phantoming Paladins and/or Inquisitors. I often use the Stone Wall ability of the pet dragon to capture a weak melee unit so that I can spend whatever time I need to recover my losses.

Paladin:
As a paladin I mix the two. Everything is average as a paladin. Your pet dragon can be used to deal damage, but it is not as strong as for a warrior. Your leadership is average but still strong enough to do the Phantom of Royal Griffins (or similar summoning unit) trick to occupy the enemy with attacking your cannon-fodder units. It is easier to get a higher int as a paladin than as a warrior so your spells can deal a fair amount of damage. Also, standard tricks like Stone Skin + Target on you tank works well for a paladin. This one works fine with all classes, especially when you meet a lot of ranged enemy units.

The unique paladin skill allows you to play reckless with one of your stacks, since it will be totally ressurected after the battle. Notice that even if you do end up loosing nothing it does not count as a no-loss battle. So in the end of the game the lost units will be included in the casualties you obtained during the game.