I managed to defeat the Fallen Paladin in over 450 rounds! :)

I didn't have any problems with this guy, as someone randomly placed him on Elone (near the River of Memory). I defeated the Inquisitors in 3 rounds with a rain of fire, and then I attacked the paladins with dragons that hatched from eggs. Luckily, he doesn't have any offensive magic – he just casts armor spells on himself. But the "old and lonely" cyclops Xerxes, with his 20+ defense and +1 speed, gave my wolves a hard time... Either you defeat him in 4-5 rounds, or you lose half your army.
And it seems like the bosses will be tough – I haven't fought any of them yet, although I'm already on Elone :o I read here how someone defeated Cthah as a Warrior – I doubt a Mage can do that.