HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

This exists in WoG, it's called the Time Market. It seems they also used it in ToE, but then removed it.

This is a good idea, it would be great to replace Cartographer with it! In the original game, for 2000 coins, it allowed you to forget one secondary skill. I agree that, especially considering how "often" Cartographer appears and how well it's guarded, it can't be called overpowered.

Also, in WoG, you could choose not 8, but 10 secondary skills (two so-called hidden ones), but that's for connoisseurs, although in my opinion, leveling up 10 secondary skills for an expert is almost an impossible task!