The most challenging maps for you.

Have you played Heroes 2? There's a scenario called "Pyramid" that's quite challenging. You have to measure every move precisely. And in Heroes 3, there's a scenario called "Titan's Winters" or something similar. On the first island, there are 3 Titan castles and 1 castle with hippos, on the second island, there are 3 Dungeon fortresses, and on the third island, there are 4 Knight fortresses? It's also a difficult scenario, and you play as the Titans. I also completed it on impossible difficulty. But for some reason, the most difficult and interesting scenario is "Champions of Gelia," I recommend you play it. IMHO