Excuse me, but I can't figure out how to attack the elementals (4000) on the First Blood map if there's no boat summon anywhere? And how to get through the blue gate to the three castles if the tent is on the other side? Unless by water?

On the Barbarian side, near the Inferno castle, there is a tent where Dess gives the Captain's Hat. Then you need to pass it to some hero, dismiss him, and buy him back at the top. And the main hero must have: Expert Water Magic and Pathfinding.
I've been replaying it God knows how many times now, and I just can't manage to take the Utopia and the hat within 2 months. My biggest achievement was when I defeated the purple player, took the Cloak of the Undead King, then killed the Arch Devils and captured the lower Knight castles. But by that time, the swamp-dwellers and elves were already too much — I had something like 300 Archangels, while they had 1500 Gold Dragons, plus the rest of their troops in the same proportions. Plus, the red player kept bothering me so often that I couldn't be away for long.