If I had engaged them in the first round (as I usually do), I would have won the battle.

Sorry for the off-topic. I tested the scenario, and I was wrong to blame the guide from Ichthyandra. If I had repeated everything exactly, it would have worked. Any of these two deviations ruin the scenario: 1) Placing the 1st Gnoll in the 1st turn in the correct cell without waiting (it gets killed by vampires on the 2nd turn). This doesn't affect the placement of the Crypt stacks in the current and next turn, but it magically affects the vampires on the 3rd turn. 2) The remaining skeleton unit needs to be finished off from your hand on the 2nd turn. I simply moved the Gnolls and Lizards to the corner. The skeleton died from the counterattack on the 2nd turn. And the vampires on the 3rd turn are already waiting and heading towards the Lizards. Perhaps the condition of the Gnolls plays a role here. It's funny, but what can you do?