Ranger – “Emerald” [5th campaign, 2nd mission]

If I'm not mistaken, there's a treasure trove of mages in the first mission. If you're lucky and have a high level of Dark Magic (why would an elf need it?), you can get the "Enchant" spell there. If you quickly capture a castle without heroes and manage to return, you can build a Capitol there. Mine stood there for the entire game without a hero. The AI didn't bother with it, and the extra 4000 gold per turn was a good bonus. Plus, there are floating debris with gold and wood. I managed to collect them before the AI ships went out to sea.