Heroes V is using LUA language.

Scripting works just as modding. If you embed it in map it will work only if the map is inside the MAPs folder. If you put it in data it will work like a MOD for the whole game.

Is it difficult? - Overall LUA is simple language but it depends on your programming knowledge. @Magnomagus wrote the code and he learned it by using internet tutorials - here is something you can start with.

How to use it for Heroes V modding? - Lets say you do read some LUA lessons or a week and want to use it for modding. The easiest way to start is by inspecting already done things, look at the code and see how they work in the game.

For example - Heroes campaigns are made with LUA. Start by inspecting them.
Here is an example on where to search for them - DATA.PAK/maps/Scenario/A2C3M4/script.lua
Also it is advisable to enable console so you can check it now and then for things that the script may print.


Some scripting information is available in /Editor documentation:
- HOMM5_A2_IDs_for_Scripts.pdf
- HOMM5_A2_Script_Functions.pdf
- HOMM5_Script_Functions.pdf

This discussion about LUA in ubi forums can be of help too.

Later on when you feel confident enough you can inspect the MMH55 scripts.

Cheers!