I have two maps in mind that look impressive. Maybe you'll find them interesting.
I've played on the Shan Hai Legend map for 24 and a half months.
There are 8 stationary boss heroes left to defeat one by one, along with the enemy castles. The editor shows that near the end of the map, you can obtain the Air book and reach the previously inaccessible enemy cities, as well as double the mana there. But before that, you need to defeat seven of them.
Tazar has become my main hero, but he clearly lacks mana.
The enemy troops are simply terrifying. Almost every other hero has the Sign of Courage or Art against Berserkers.
Here's an example of the next battle I'm facing; Berserkers don't work here.
There are no Vulnerability medals on the map.