The problem, as somebody mentioned way earlier in the thread, is that you need to go into the module and change the tokens used by some of the enemies, since the tokens are re-used so much. It's not as simple as just replacing all the tokens.
You could also go the route of finding better art that at the same time looks similar enough to faces/poses/etc. of the originals (like the succubus/beautiful woman issue brought up earlier, if it's a pretty face without horns, sharp ears and red skin, then use some picture of a pretty face without horns and other demonic features). A bigger issue is that humanoid tokens are too fucking gender-ambiguous and I accidentally made some cultist brother a woman because his token wasn't masculine enough.
Also keep square 64x64 art pieces of all tokens as FramedIcons subfolder for dialogue pics is pretty much 99% of the token art except it's square/uncut. Almost all filenames are the same, minus the "-1" size suffix, though there are instances of some files getting a prefix or a suffix, the suffix changing (e.g. commander-1 -> human-commander-alt, or "red" in the name changing to "fire"), and in a few instances the icon getting a completely different name from the token. And a few icons are from tokens that have no 64x versions (like spiders) so it's a bit of additional cropping/resizing. And while at token-replacement, you need to replace vanilla player character art as well, as a few creatures use that instead of the main token folder (even though player tokens are duplicated in the main folder).
Another thing I noticed when making my pack is Pierre made a token for a non-elf from an elf one by zooming the art in a bit so the elf ear is not visible, and cut out characters from the KotC1 cover art to make a few more tokens with them. Trying to squeeze every last bit of art he could.
Unless someone has a better way to automatize this.
XnConvert can do quick multi-step batch/folder edits with everything base XnView can - bulk resizing, cropping, color depth changes (for when you're making square tokens and need to make them 32bit for the game to recognize them), etc; I think you can also do color transparency via importing a mask from a file and then doing some other step but I don't remember what it was.
It's not
that time-consuming, either way. Finding the right art will likely take you more time than editing it.
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Also someone could try converting Dominions sprites (as tokens). Fairly sure I've seen a complete art rip for modding purposes on either Steam or the fan forums, and there were some D&D-themed nation mods for the previous game versions too. I'll probaly eventually try doing some custom shadows for sprite use (or they could be simply pasted into some token template), but I already wasted enough time on that giant token pack.