Taking of the Necropolis [COMPLETE EDITION]

The problem is that there is no universally applicable strategy for the Swamp faction, unfortunately. Ihtiandr, I sometimes play Heroes, and sometimes I choose the Swamp and Dungeon factions, it happens. :-)
It all depends on the map being played. For example, with a 200% bonus, I would upgrade the Gnolls and, while deflecting attacks, attack the Vampires. Adding 2 attack points to the Hero would be enough. In any case, you can get a maximum number of Crypts with acceptable losses, but I don't consider the existing Swamp strategy to be universal. In my opinion, you either need to add Viv or Gr. Lizards.

which works in more than 50% of cases.

Not 50%. I'm willing to do 10 generations, and in half of them, there won't be the necessary Gnolls or Lizards, and with lower values, the strategy is no longer universal.