Walkthroughs for custom maps.

Surprisingly, I managed to defeat this enemy without any external help or hints, and this battle didn't drive me crazy. The right tactic soon became clear: I needed to use the obstacles, and exactly as shown in your screenshot. It was easier for me, though, because I fought the Encounter later and with a larger army. It's convenient that he stands still in the field, and his army can't increase.
And yesterday, I accidentally saw a recording of your battle with the Gold Keeper, and what do you know: you used the clone bug! :) Awesome!

I've seen how to kill the Gold Keeper the normal way, but that would require me to buy troops to break through the antimagic garrison with phoenixes, which means wasting money and resources. The last time I bought troops extensively was before King Darius; after that, I only gathered creatures from external lairs. In general, the map is poorly designed. The treasure hoard in Rampart is built too late, so even with my ultra-economy, I'll have to spend several months gathering money and resources. As an alternative, the author could have placed a Pandora's Box with resources behind a guard, requiring the player to kill Overlord Hex before the sixth month. That would be fine. As it is, I'm not sure I can break through with 600 archers. And then, it seems, I'll have to spend many months doing nothing :(