Actually I think no losses is easier in AP than in TL, even as a Mage. I am up to 159 battles without loss in my Impossible Mage game, and while it hasn't always been easy, it is certainly doable.
For me the keys are high intellect (over 40 for me at level 31), maxed Summoner ability for Phantomed Paladins (up to 81% now), as high leadership as you can possibly get (about 13,000 at level 31) and a few other things. I am using a team of Paladins, Inquisitors, Knights, Giants and Archmages. The Giants and Knights aren't essential, and in fact the Knights rarely seem to get into the action at the moment. Horsemen could be used instead. It's pretty simple. Sometimes I use Stone Skin + Target on the Giants on turn 1 (plus Archmages' Magic Shield) if I think I will absorb too much damage from ranged units. If that isn't necessary, I use Trap (I have the Trapper medal 3 and over 7000 damage on a level 3 Trap), or also Fire Arrow/Fireball. The baby dragon is mainly used for Mana Accelerator. So you smash the enemy but leave one pitiful unit left (preferably a ranged unit that won't get itself killed) and arrange your troops in a ring around the Paladin. This doesn't work for the Giants (or any other level 5 unit), but that's okay, as that's where the Inquisitors come into play. If you need more than one resurrection on the Giants, you can Phantom more Inquisitors. So it might take two or sometimes three Phantomed Paladin stacks to return all stacks to full health, and then ZAP! I hit the remaining stack with the Archmages.
