The Necromancer's Path.

I completed this scenario on Hero difficulty.

Walkthrough

You can't lose the starting town, so I tried to learn the portal to the town as quickly as possible. Experience from neutral creatures was reduced, so I took chests for experience. On day 15, I obtained a +20% experience chainmail. On the fourth week, Giovanni arrived and chased my secondary heroes, then went to his territory. I learned the portal to the town, and Benedict (medium difficulty) arrived. I prepared to defend the castle, but he just killed Naadir and used the portal to the town himself. Then I killed Giovanni in his territory (losses: 30 ghosts, 5 zombies, 5 liches). He was resurrected with a large army and also increased his stats. I quickly returned to the town because the orc Kagraag was already running there. The following situation arose: there are three strong enemy heroes who don't want to attack Arantir in the castle, and fighting them in the field... I didn't even want to try. The Knight kept reaching my castle and using the portal to the town, and Giovanni killed the orc and also returned to his town (if Arantir approached him). Arantir only had time to go and defeat some neutral creatures and was forced to return to the town again. This happened several times, but then the Knight arrived again and this time finally attacked the town. He has a large army, with 186 horses. I defeated him using Darkness, and in the end, I spent a long time raising troops, resulting in losses of 2 liches. I had very bad luck with mentorship; after 27 levels, I still didn't get it. Only the "mentor" helped (who also sells spellbooks, a trading post, and keys... interesting). I trained additional heroes, leaving only vampires for Arantir, and Kaspar took the rest of the army and blocked the exit from the portal for Giovanni. Benedict and Kagraag were already being killed by a single squad of vampires at this stage. I captured Mortred (killed Benedict in the castle), and the orc was distracted by a caravan from Mortred, which allowed me to capture his town (there is a huge army there, but it's easy with Darkness). Then I defeated the orc in the field. This was already in the middle of the eighth month. I went to Vessel, looked at his combat cheats, used load games to determine the growth formula, and... went to build up my army. It's as if he gets an army from four towns. We only have three towns, but we have many dwellings and necromancy, so we are ahead. Then a purely necromancer-style game of attrition began: we calmly explore the map, defeating neutral creatures, strictly one squad per week, to raise more from necromancy. Before that, I took the trophies (removed Summoning) to ensure that there was enough money to buy back all the troops. This is how I killed all the neutral creatures, with only the witches in Giovanni's territory remaining, and they are far away. Giovanni, by the way, was building up his army all this time. I released him from the portal, and Arantir easily killed him, with almost no losses. I left 50 messengers and 100 liches for Kaspar to continue blocking the exit for Giovanni, and he could also summon reinforcements from the town. Arantir changed his skills with the mentor, taking into account the size of the army, and went to Vessel. I punished the cheater, even without using Berserk and Subdue . Bertrand appeared, with low difficulty, but it's better not to fight him in the field; he has huge combat stats. He didn't attack the town, so I left Arantir with all the vampires + 100 liches + 5 ghosts, and hid the rest of the army in the mine. Now Bertrand agreed to attack the castle, and I managed to win without losses, but this was the final battle. Victory in 395 days. It's a lot, but I often skipped turns at the end to restore dark energy; in real time, it's quick.

The walkthrough was long, but quite comfortable, surprisingly. Yes, the enemies force you to play slowly and defensively... But I chose the path of the necromancer: with BD=0, I looked at this situation and just built up my army . My impressions of the scenario are positive: good additional quests, the plot is well-developed, there are many cutscenes, and there were also interesting battles. I saved the replays; I know you like that.
Thank you very much for the map!