In my mod, I use:
New Creature Framework (new creature IDs)
New Artifact Framework (new artifact IDs)
New Hero Class Framework (new hero class IDs)
All of this involves modifying the game's launcher (.Exe) at its core. These YML files interfere with it and force it to "recognize/know/use" the changes in the types.xml list, which is stored in the data archive.

At one time, I downloaded them from this forum and manually configured them (I copied data from NSF into types.xml and added lines for 999 creatures + placeholder creatures). It's important to maintain all the connections so that the game doesn't crash.
I don't quite remember about NAF, but it was simpler than with NSF (and it's not that difficult to take a template link to an artifact and replace all the "original" content with the copied content, it just takes time and effort).
I think I found NHCF somewhere on Dreadknight's site, and Waterfall has a video in the video tutorials section – a recording of a stream where I added a new class to the game.

So, there are two options: either you download mods in parts and reconfigure them to suit your needs, as I did. Or you download Armageddon's Blade and overwrite my additions with template links, and then, after clearing everything, you start doing what you want.