Diamond Monster

A lair of Hydras was guarded by 42 monks. For those who like calculations, please provide an explanation.

The map has 3 swamp zones out of 16. In this case, the Hydra lair has a value of 11072 and is guarded by 34-56 (an average of 45) monks.
You knew about two swamp zones with 100% certainty. If we assume that there isn't a third one, we could predict the lair's value to be 8755 and its guard to be 25-41 (an average of 33) monks.

In general, it seems to be known that more monks are generated than necessary. This is related to a bug in their AI Value: it doesn't take shooting into account. In the original, their AI Value is 485. According to my calculations, the real value should be around 582. Then, with 3 swamp zones, the guard would be 29-47 (an average of 38) monks, and with two swamp zones, 21-35 (an average of 28) monks. That is, approximately the same as the number of Crusaders that are generated.