My squad against Karador was:
1) snakes
2) royal snakes
both boosted with "royal snake ring" which gives +3 dmg, royals have no retaliation
3) dryads
boosted with "Anga's Ruby", no retaliation
4) pirates
Their "sweeping strike" is very useful in "crowded" areas
5) black unicorns
Holy strike +30% dmg to undead
I do not recommend inquisitors/priests since they're very poor in hand-to-hand combat. To be precise, any shooting unit will be useless.
As a mage i used Fire Rain, Phantom, maybe Blind on skeleton archers
Royal Snakes turned out to be most damaging unit, when unicorns were killed in a middle of the fight (could used ancient ents instead)
Good Luck
