Outcast's Path

With Necropolis, you'll need money for caravans, but at least you'll have a decent army. The hero has enough dark magic, plus they have more flying units, for sure. (In the end, I only had wyverns left among my flying units, which were stationed near the human city as support.)

It's better to give the Temple city at the very end, or conversely, at the beginning, so that the army can build up for the final assault.