Play as Axel.

Axel isn't particularly special at the beginning of the game, but once you have some extra gold, he becomes a killing machine. Specializing in level 6 creatures is already a huge advantage, as in the fifth installment, two level 6 creatures are roughly equal to one level 7 creature, unlike other parts of the game where the last level usually significantly surpasses the previous one. For every 2 levels, the Knights will receive +1 to attack and defense, so at level 40, they will have +20 to attack and defense, which will increase the damage they deal by 100% and reduce the damage they receive by 50%. But that's not all; thanks to the faction skill "Preparation," you can upgrade lower-level troops to Knights. In a week, you can prepare 20 creatures, upgrade 6 Monks to Knights, leaving 14, upgrade 7 Footmen to Monks, and then Monks to Knights, resulting in +13 Knights per week, or a total of 17 level 6 creatures that you can consistently obtain every week. Overall, in my opinion, Axel is the strongest hero in the game, and I often play as him.