Interesting. I just Googled to see where the "Zemsta Mutare" map is available. As I expected, I only found links to heroes3.eu and our forum, as well as my recent comment on YouTube. But unexpectedly, I found this map on a website I hadn't seen before: http://www.heroes3maps.com/ I found out that it is only 32 days old. The creators write that they want to collect the largest collection of custom maps for "Heroes 3". It says that they have a total of 12047 maps, including maps in different languages, including Russian and Chinese, and some of them were recently uploaded to HeroesPortal. There is a convenient search and information about the maps. Registration is not required to download (I checked).
There is a correctly displayed Polish description for "Zemsta Mutare", which I translated into Russian using Google:

The board is extremely difficult; it is the last, decisive board for victory and proving that Mutare is the ruler of the Dungeon. To win it, you must kill the Dragon who captured the Castle and killed Dace. Seers and their good rewards will help you win the board. The continuation of the map description is in the 1st day of the game.

The council is extremely difficult. This is the last, decisive council about victory and proof that Mutare is the ruler of the Dungeon. To win it, you must kill the Dragon who captured the Castle and killed Dace. Seers and their good rewards will help you win the board. The continuation of the map description is in the 1st day of the game.