A program for calculating the strength of the guard on random maps in Heroes of Might and Magic III, called H3CalcGuards.

At least, the fact that such a "Pandora" has a value of 15000 is definitely correct. You can check the map description in the scenario information: if it says "monsters 5," it means that when respawning, you need to take a "Guard strength" that is 1 point stronger than usual (the treasure already has the maximum value, so this enhancement of the guard does not affect it).