Invasion

I played your map. It has its own unique style. But I wouldn't say it was difficult. At first, it seems like it will be challenging, but when you reach the first Barbarian, he has nothing to resist us with. The enemies simply don't have enough gold to replenish their forces, even on the impossible difficulty level. The Knight in the dungeon isn't really needed, because when (and if) you gather enough strength to break through the phoenixes guarding the tent leading to the Knight, your starting Sorceress is already strong enough. And before that, breaking through these firebirds means losing a lot of archers, which is unlikely to be acceptable. Only the final stage was challenging, when everything is destroyed except for the main boss, and you just run (or teleport with Townportal) between cities, accumulating enough strength.
And yes, it's unclear why all these mines and treasures are there – to spend on the market? But even without them, you have plenty of gold by the end of the game from the gold mines.
On the other hand, I liked the landscape and the map's design.