Battle against Karador on impossible

[Metathron]

God I hate the fight with Karador.

Even on just the hard difficulty I'm finding the battle super frustrating. Perhaps at level 22 I jumped on it too soon, but I thought I could do a good job with an army of unicorns, black unicorns, griffins, ents and royal snakes. My paladin's stats were something like A16, D19, I21 plus I had the shield that gives you +25% defense against undead attacks and the vampire cloak thingy that decreases the enemy's attack by -30% during nighttime (and night it was). And still I ended up losing, the constant raising of the dead proved too much for my forces.

Will give it another shot later, after I grab the +1200 leadership at level 24. But I was wondering if the above is a good army to tackle him, or if I should stick with the 3-girl + green dragons + royal snakes composition.