Angels and paladins – how to use them? There are also discussions about them here.

So, here's my personal strategy for playing as Haven. Levels 1-3 are solely for claiming territories, i.e., capturing mines, etc. I don't hire Griffins at all. They are expensive and "short-lived" creatures. I also don't build the Inquisitor building, nor the Militia building. So, the mines are captured. Next, you need to build a Hippodrome and hire 10 Paladins. With them, you can complete the entire map. :)

But if you prefer to play for development... you can continue this scheme. You accumulate 120k gold, upgrade the hero's skills for training, and build the corresponding buildings. You hire Monks (~40) and train them into Knights, and then into Paladins. At the same time, you can hire Griffins, of which you will have accumulated quite a few by that time, or hire Archangels, or train Archers from Peasants.