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Thanks to everyone for the tips; I wouldn't have managed without them. Here's what worked for me: 1. First, you need crystals to close the portals. When choosing hero skills before starting the map, there's one that reduces the cost of trading on the market. With it, crystals cost only 625 gold instead of 2500. You can also level up a secondary hero's skill (the second row of the first column, either in the second or third tab when distributing skill points), which will reduce the cost further to 500. 2. If you go from the starting castle down to the fort and then to the right, you'll find a building in the Necromancer color scheme. Winning gives you 50 crystals and a lot of gold, which is very helpful at the beginning. 3. The annoying enemy hero who attacks with fire and a chain of lightning, wiping out half your army. You just have to endure him at the beginning, trying not to let him take a second turn. Also, I bought everything on the market that provides magic resistance. If you're unlucky, at least get items that protect against fire or air magic separately. 4. The key task in the early phase of the game is to capture the second castle (it's down to the fort and then along the road to the right of the starting castle). From there, you can go up, and there will be a crystal mine, where you can place a secondary hero and hold the mine if you don't capture the fort. 5. The entrance to the worm boss will be in the initial castle, not in the collapsed mines. You can only gather more crystals in the mines if you haven't already. What didn't work: 1. I tried to use a secondary hero on a ship to sail to the island in the upper left corner of the map and take control of the crystal mine there, but an enemy hero quickly arrives and defeats the hero. So, if I were to play again, I would just sail the ship everywhere and collect resources in the sea and on the shores of the islands. If you go deeper into the islands with forts, you'll again encounter enemy heroes. Good luck to everyone!