Scripts

Each hero gains 2 points to magic at the very last day of the month. How do I implement this condition?

Do you mean checking if it's currently the last day of the month? For example, like this:

if ((GetDate(WEEK) == 4) and (GetDate(DAY_OF_WEEK) == 7)) then ...

I want these creatures on the map to appear as single units but have larger stacks in battle.

In the editor, disable their weekly growth; remove the standard touch handler from the scripts and replace it with your own. I recently provided a link explaining how to do this. In your custom handler, launch any kind of battle using StartCombat(). This function also has the ability to specify a callback (the name of another function that will be called after its completion, i.e., after the battle). In this callback, check if the hero won and delete the corresponding unit.

How can I disable Astral Gate and Portal to Town spells on the map?

In the map settings within the editor, there is a "Spells" tab where you can remove unnecessary ones.

I set up a quest at the Seer's Hut and chose "Army" as the reward type. Where do I enter which creatures to give?

Try right-clicking on the item related to the reward type or the one following it; there should be an "Add" option in the menu. All of this was described in great detail in one of the official manuals included with the game files.

Also, how do I set a specific number of creatures in a Crypt?

Crypt, are you referring to a treasure chamber? Either through modding by editing the game resources, or again, remove the standard handler, implement your own, and trigger any desired battle via StartCombat().