The most challenging campaign.

A cult servant for the Warlock. Kifra, Letos, Sinithar, and Vaishan, level 20, against Railag and Shadia, level 16, in the first week – a clear mismatch. I could only complete it normally without bugs on version 1.0, but there, the path led to Shadia's castle, and she captured it on the first day. On versions 1.6 and 3.1, there's a bug: the demon just stands there, like a fish on ice. I understand that I could have completed it even with weekly raids – the skill level is high enough – but nevertheless, this mission is the most difficult.
No other problems arose. "Conquest" for Agrail is also not easy, but it was completed.
And the campaign about Zehir was enjoyable: replaying it as a shaman is awesome.
All on a hero, of course.