Two sisters.

Defeating opponents who prevent you from advancing even a single step into their territory is also a unique challenge in this map.

I'm already in their lands. I've captured three castles. And I've defeated Hangwul and Rolf, as well as other heroes, multiple times. Apparently, my expectations were too high after playing as the Necromancer. I thought it would be something similar to those dwarves in the video. As they say, your expectations are your own problem.